1. 13 Sep, 2013 1 commit
  2. 12 Sep, 2013 39 commits
    • Linus Torvalds's avatar
      Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus · 5a7d8a28
      Linus Torvalds authored
      Pull MIPS updates from Ralf Baechle:
       "This has been sitting in -next for a while with no objections and all
        MIPS defconfigs except one are building fine; that one platform got
        broken by another patch in your tree and I'm going to submit a patch
        separately.
      
         - a handful of fixes that didn't make 3.11
         - a few bits of Octeon 3 support with more to come for a later
           release
         - platform enhancements for Octeon, ath79, Lantiq, Netlogic and
           Ralink SOCs
         - a GPIO driver for the Octeon
         - some dusting off of the DECstation code
         - the usual dose of cleanups"
      
      * 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (65 commits)
        MIPS: DMA: Fix BUG due to smp_processor_id() in preemptible code
        MIPS: kexec: Fix random crashes while loading crashkernel
        MIPS: kdump: Skip walking indirection page for crashkernels
        MIPS: DECstation HRT calibration bug fixes
        MIPS: Export copy_from_user_page() (needed by lustre)
        MIPS: Add driver for the built-in PCI controller of the RT3883 SoC
        MIPS: DMA: For BMIPS5000 cores flush region just like non-coherent R10000
        MIPS: ralink: Add support for reset-controller API
        MIPS: ralink: mt7620: Add cpu-feature-override header
        MIPS: ralink: mt7620: Add spi clock definition
        MIPS: ralink: mt7620: Add wdt clock definition
        MIPS: ralink: mt7620: Improve clock frequency detection
        MIPS: ralink: mt7620: This SoC has EHCI and OHCI hosts
        MIPS: ralink: mt7620: Add verbose ram info
        MIPS: ralink: Probe clocksources from OF
        MIPS: ralink: Add support for systick timer found on newer ralink SoC
        MIPS: ralink: Add support for periodic timer irq
        MIPS: Netlogic: Built-in DTB for XLP2xx SoC boards
        MIPS: Netlogic: Add support for USB on XLP2xx
        MIPS: Netlogic: XLP2xx update for I2C controller
        ...
      5a7d8a28
    • Linus Torvalds's avatar
      Merge tag 'xfs-for-linus-v3.12-rc1-2' of git://oss.sgi.com/xfs/xfs · e0ea4045
      Linus Torvalds authored
      Pull xfs update #2 from Ben Myers:
       "Here we have defrag support for v5 superblock, a number of bugfixes
        and a cleanup or two.
      
         - defrag support for CRC filesystems
         - fix endian worning in xlog_recover_get_buf_lsn
         - fixes for sparse warnings
         - fix for assert in xfs_dir3_leaf_hdr_from_disk
         - fix for log recovery of remote symlinks
         - fix for log recovery of btree root splits
         - fixes formemory allocation failures with ACLs
         - fix for assert in xfs_buf_item_relse
         - fix for assert in xfs_inode_buf_verify
         - fix an assignment in an assert that should be a test in
           xfs_bmbt_change_owner
         - remove dead code in xlog_recover_inode_pass2"
      
      * tag 'xfs-for-linus-v3.12-rc1-2' of git://oss.sgi.com/xfs/xfs:
        xfs: remove dead code from xlog_recover_inode_pass2
        xfs: = vs == typo in ASSERT()
        xfs: don't assert fail on bad inode numbers
        xfs: aborted buf items can be in the AIL.
        xfs: factor all the kmalloc-or-vmalloc fallback allocations
        xfs: fix memory allocation failures with ACLs
        xfs: ensure we copy buffer type in da btree root splits
        xfs: set remote symlink buffer type for recovery
        xfs: recovery of swap extents operations for CRC filesystems
        xfs: swap extents operations for CRC filesystems
        xfs: check magic numbers in dir3 leaf verifier first
        xfs: fix some minor sparse warnings
        xfs: fix endian warning in xlog_recover_get_buf_lsn()
      e0ea4045
    • Linus Torvalds's avatar
      Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending · 48efe453
      Linus Torvalds authored
      Pull SCSI target updates from Nicholas Bellinger:
       "Lots of activity again this round for I/O performance optimizations
        (per-cpu IDA pre-allocation for vhost + iscsi/target), and the
        addition of new fabric independent features to target-core
        (COMPARE_AND_WRITE + EXTENDED_COPY).
      
        The main highlights include:
      
         - Support for iscsi-target login multiplexing across individual
           network portals
         - Generic Per-cpu IDA logic (kent + akpm + clameter)
         - Conversion of vhost to use per-cpu IDA pre-allocation for
           descriptors, SGLs and userspace page pointer list
         - Conversion of iscsi-target + iser-target to use per-cpu IDA
           pre-allocation for descriptors
         - Add support for generic COMPARE_AND_WRITE (AtomicTestandSet)
           emulation for virtual backend drivers
         - Add support for generic EXTENDED_COPY (CopyOffload) emulation for
           virtual backend drivers.
         - Add support for fast memory registration mode to iser-target (Vu)
      
        The patches to add COMPARE_AND_WRITE and EXTENDED_COPY support are of
        particular significance, which make us the first and only open source
        target to support the full set of VAAI primitives.
      
        Currently Linux clients are lacking upstream support to actually
        utilize these primitives.  However, with server side support now in
        place for folks like MKP + ZAB working on the client, this logic once
        reserved for the highest end of storage arrays, can now be run in VMs
        on their laptops"
      
      * 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (50 commits)
        target/iscsi: Bump versions to v4.1.0
        target: Update copyright ownership/year information to 2013
        iscsi-target: Bump default TCP listen backlog to 256
        target: Fix >= v3.9+ regression in PR APTPL + ALUA metadata write-out
        iscsi-target; Bump default CmdSN Depth to 64
        iscsi-target: Remove unnecessary wait_for_completion in iscsi_get_thread_set
        iscsi-target: Add thread_set->ts_activate_sem + use common deallocate
        iscsi-target: Fix race with thread_pre_handler flush_signals + ISCSI_THREAD_SET_DIE
        target: remove unused including <linux/version.h>
        iser-target: introduce fast memory registration mode (FRWR)
        iser-target: generalize rdma memory registration and cleanup
        iser-target: move rdma wr processing to a shared function
        target: Enable global EXTENDED_COPY setup/release
        target: Add Third Party Copy (3PC) bit in INQUIRY response
        target: Enable EXTENDED_COPY setup in spc_parse_cdb
        target: Add support for EXTENDED_COPY copy offload emulation
        target: Avoid non-existent tg_pt_gp_mem in target_alua_state_check
        target: Add global device list for EXTENDED_COPY
        target: Make helpers non static for EXTENDED_COPY command setup
        target: Make spc_parse_naa_6h_vendor_specific non static
        ...
      48efe453
    • Linus Torvalds's avatar
      Merge branch 'akpm' (patches from Andrew Morton) · ac4de954
      Linus Torvalds authored
      Merge more patches from Andrew Morton:
       "The rest of MM.  Plus one misc cleanup"
      
      * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (35 commits)
        mm/Kconfig: add MMU dependency for MIGRATION.
        kernel: replace strict_strto*() with kstrto*()
        mm, thp: count thp_fault_fallback anytime thp fault fails
        thp: consolidate code between handle_mm_fault() and do_huge_pmd_anonymous_page()
        thp: do_huge_pmd_anonymous_page() cleanup
        thp: move maybe_pmd_mkwrite() out of mk_huge_pmd()
        mm: cleanup add_to_page_cache_locked()
        thp: account anon transparent huge pages into NR_ANON_PAGES
        truncate: drop 'oldsize' truncate_pagecache() parameter
        mm: make lru_add_drain_all() selective
        memcg: document cgroup dirty/writeback memory statistics
        memcg: add per cgroup writeback pages accounting
        memcg: check for proper lock held in mem_cgroup_update_page_stat
        memcg: remove MEMCG_NR_FILE_MAPPED
        memcg: reduce function dereference
        memcg: avoid overflow caused by PAGE_ALIGN
        memcg: rename RESOURCE_MAX to RES_COUNTER_MAX
        memcg: correct RESOURCE_MAX to ULLONG_MAX
        mm: memcg: do not trap chargers with full callstack on OOM
        mm: memcg: rework and document OOM waiting and wakeup
        ...
      ac4de954
    • Chen Gang's avatar
      mm/Kconfig: add MMU dependency for MIGRATION. · de32a817
      Chen Gang authored
      
      
      MIGRATION must depend on MMU, or allmodconfig for the nommu sh
      architecture fails to build:
      
          CC      mm/migrate.o
        mm/migrate.c: In function 'remove_migration_pte':
        mm/migrate.c:134:3: error: implicit declaration of function 'pmd_trans_huge' [-Werror=implicit-function-declaration]
           if (pmd_trans_huge(*pmd))
           ^
        mm/migrate.c:149:2: error: implicit declaration of function 'is_swap_pte' [-Werror=implicit-function-declaration]
          if (!is_swap_pte(pte))
          ^
        ...
      
      Also let CMA depend on MMU, or when NOMMU, if we select CMA, it will
      select MIGRATION by force.
      Signed-off-by: default avatarChen Gang <gang.chen@asianux.com>
      Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      de32a817
    • Jingoo Han's avatar
      kernel: replace strict_strto*() with kstrto*() · 6072ddc8
      Jingoo Han authored
      
      
      The usage of strict_strto*() is not preferred, because strict_strto*() is
      obsolete.  Thus, kstrto*() should be used.
      Signed-off-by: default avatarJingoo Han <jg1.han@samsung.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6072ddc8
    • David Rientjes's avatar
      mm, thp: count thp_fault_fallback anytime thp fault fails · 17766dde
      David Rientjes authored
      
      
      Currently, thp_fault_fallback in vmstat only gets incremented if a
      hugepage allocation fails.  If current's memcg hits its limit or the page
      fault handler returns an error, it is incorrectly accounted as a
      successful thp_fault_alloc.
      
      Count thp_fault_fallback anytime the page fault handler falls back to
      using regular pages and only count thp_fault_alloc when a hugepage has
      actually been faulted.
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      17766dde
    • Kirill A. Shutemov's avatar
      thp: consolidate code between handle_mm_fault() and do_huge_pmd_anonymous_page() · c0292554
      Kirill A. Shutemov authored
      
      
      do_huge_pmd_anonymous_page() has copy-pasted piece of handle_mm_fault()
      to handle fallback path.
      
      Let's consolidate code back by introducing VM_FAULT_FALLBACK return
      code.
      Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Acked-by: default avatarHillf Danton <dhillf@gmail.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Andi Kleen <ak@linux.intel.com>
      Cc: Matthew Wilcox <willy@linux.intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c0292554
    • Kirill A. Shutemov's avatar
      thp: do_huge_pmd_anonymous_page() cleanup · 128ec037
      Kirill A. Shutemov authored
      
      
      Minor cleanup: unindent most code of the fucntion by inverting one
      condition.  It's preparation for the next patch.
      
      No functional changes.
      Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Acked-by: default avatarHillf Danton <dhillf@gmail.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Andi Kleen <ak@linux.intel.com>
      Cc: Matthew Wilcox <willy@linux.intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      128ec037
    • Kirill A. Shutemov's avatar
      thp: move maybe_pmd_mkwrite() out of mk_huge_pmd() · 3122359a
      Kirill A. Shutemov authored
      
      
      It's confusing that mk_huge_pmd() has semantics different from mk_pte() or
      mk_pmd().  I spent some time on debugging issue cased by this
      inconsistency.
      
      Let's move maybe_pmd_mkwrite() out of mk_huge_pmd() and adjust prototype
      to match mk_pte().
      Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Acked-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Andi Kleen <ak@linux.intel.com>
      Cc: Matthew Wilcox <willy@linux.intel.com>
      Cc: Hillf Danton <dhillf@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3122359a
    • Kirill A. Shutemov's avatar
      mm: cleanup add_to_page_cache_locked() · 66a0c8ee
      Kirill A. Shutemov authored
      
      
      Make add_to_page_cache_locked() cleaner:
      
       - unindent most code of the function by inverting one condition;
       - streamline code no-error path;
       - move insert error path outside normal code path;
       - call radix_tree_preload_end() earlier;
      
      No functional changes.
      Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Acked-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Andi Kleen <ak@linux.intel.com>
      Cc: Matthew Wilcox <willy@linux.intel.com>
      Cc: Hillf Danton <dhillf@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      66a0c8ee
    • Kirill A. Shutemov's avatar
      thp: account anon transparent huge pages into NR_ANON_PAGES · 3cd14fcd
      Kirill A. Shutemov authored
      
      
      We use NR_ANON_PAGES as base for reporting AnonPages to user.  There's
      not much sense in not accounting transparent huge pages there, but add
      them on printing to user.
      
      Let's account transparent huge pages in NR_ANON_PAGES in the first place.
      Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Acked-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Andi Kleen <ak@linux.intel.com>
      Cc: Matthew Wilcox <willy@linux.intel.com>
      Cc: Hillf Danton <dhillf@gmail.com>
      Cc: Ning Qu <quning@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3cd14fcd
    • Kirill A. Shutemov's avatar
      truncate: drop 'oldsize' truncate_pagecache() parameter · 7caef267
      Kirill A. Shutemov authored
      truncate_pagecache() doesn't care about old size since commit
      cedabed4
      
       ("vfs: Fix vmtruncate() regression").  Let's drop it.
      Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7caef267
    • Chris Metcalf's avatar
      mm: make lru_add_drain_all() selective · 5fbc4616
      Chris Metcalf authored
      
      
      make lru_add_drain_all() only selectively interrupt the cpus that have
      per-cpu free pages that can be drained.
      
      This is important in nohz mode where calling mlockall(), for example,
      otherwise will interrupt every core unnecessarily.
      
      This is important on workloads where nohz cores are handling 10 Gb traffic
      in userspace.  Those CPUs do not enter the kernel and place pages into LRU
      pagevecs and they really, really don't want to be interrupted, or they
      drop packets on the floor.
      Signed-off-by: default avatarChris Metcalf <cmetcalf@tilera.com>
      Reviewed-by: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5fbc4616
    • Sha Zhengju's avatar
      memcg: document cgroup dirty/writeback memory statistics · 9cb2dc1c
      Sha Zhengju authored
      
      Signed-off-by: default avatarSha Zhengju <handai.szj@taobao.com>
      Cc: Fengguang Wu <fengguang.wu@intel.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9cb2dc1c
    • Sha Zhengju's avatar
      memcg: add per cgroup writeback pages accounting · 3ea67d06
      Sha Zhengju authored
      Add memcg routines to count writeback pages, later dirty pages will also
      be accounted.
      
      After Kame's commit 89c06bd5
      
       ("memcg: use new logic for page stat
      accounting"), we can use 'struct page' flag to test page state instead
      of per page_cgroup flag.  But memcg has a feature to move a page from a
      cgroup to another one and may have race between "move" and "page stat
      accounting".  So in order to avoid the race we have designed a new lock:
      
               mem_cgroup_begin_update_page_stat()
               modify page information        -->(a)
               mem_cgroup_update_page_stat()  -->(b)
               mem_cgroup_end_update_page_stat()
      
      It requires both (a) and (b)(writeback pages accounting) to be pretected
      in mem_cgroup_{begin/end}_update_page_stat().  It's full no-op for
      !CONFIG_MEMCG, almost no-op if memcg is disabled (but compiled in), rcu
      read lock in the most cases (no task is moving), and spin_lock_irqsave
      on top in the slow path.
      
      There're two writeback interfaces to modify: test_{clear/set}_page_writeback().
      And the lock order is:
      	--> memcg->move_lock
      	  --> mapping->tree_lock
      Signed-off-by: default avatarSha Zhengju <handai.szj@taobao.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Reviewed-by: default avatarGreg Thelen <gthelen@google.com>
      Cc: Fengguang Wu <fengguang.wu@intel.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3ea67d06
    • Sha Zhengju's avatar
      memcg: check for proper lock held in mem_cgroup_update_page_stat · 658b72c5
      Sha Zhengju authored
      
      
      We should call mem_cgroup_begin_update_page_stat() before
      mem_cgroup_update_page_stat() to get proper locks, however the latter
      doesn't do any checking that we use proper locking, which would be hard.
      Suggested by Michal Hock we could at least test for rcu_read_lock_held()
      because RCU is held if !mem_cgroup_disabled().
      Signed-off-by: default avatarSha Zhengju <handai.szj@taobao.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Reviewed-by: default avatarGreg Thelen <gthelen@google.com>
      Cc: Fengguang Wu <fengguang.wu@intel.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      658b72c5
    • Sha Zhengju's avatar
      memcg: remove MEMCG_NR_FILE_MAPPED · 68b4876d
      Sha Zhengju authored
      
      
      While accounting memcg page stat, it's not worth to use
      MEMCG_NR_FILE_MAPPED as an extra layer of indirection because of the
      complexity and presumed performance overhead.  We can use
      MEM_CGROUP_STAT_FILE_MAPPED directly.
      Signed-off-by: default avatarSha Zhengju <handai.szj@taobao.com>
      Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Acked-by: default avatarFengguang Wu <fengguang.wu@intel.com>
      Reviewed-by: default avatarGreg Thelen <gthelen@google.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      68b4876d
    • Sha Zhengju's avatar
      memcg: reduce function dereference · 1a36e59d
      Sha Zhengju authored
      
      
      This function dereferences res far too often, so optimize it.
      Signed-off-by: default avatarSha Zhengju <handai.szj@taobao.com>
      Signed-off-by: default avatarQiang Huang <h.huangqiang@huawei.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
      Cc: Jeff Liu <jeff.liu@oracle.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1a36e59d
    • Sha Zhengju's avatar
      memcg: avoid overflow caused by PAGE_ALIGN · 3af33516
      Sha Zhengju authored
      
      
      Since PAGE_ALIGN is aligning up(the next page boundary), so after
      PAGE_ALIGN, the value might be overflow, such as write the MAX value to
      *.limit_in_bytes.
      
        $ cat /cgroup/memory/memory.limit_in_bytes
        18446744073709551615
      
        # echo 18446744073709551615 > /cgroup/memory/memory.limit_in_bytes
        bash: echo: write error: Invalid argument
      
      Some user programs might depend on such behaviours(like libcg, we read
      the value in snapshot, then use the value to reset cgroup later), and
      that will cause confusion.  So we need to fix it.
      Signed-off-by: default avatarSha Zhengju <handai.szj@taobao.com>
      Signed-off-by: default avatarQiang Huang <h.huangqiang@huawei.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
      Cc: Jeff Liu <jeff.liu@oracle.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3af33516
    • Sha Zhengju's avatar
      memcg: rename RESOURCE_MAX to RES_COUNTER_MAX · 6de5a8bf
      Sha Zhengju authored
      
      
      RESOURCE_MAX is far too general name, change it to RES_COUNTER_MAX.
      Signed-off-by: default avatarSha Zhengju <handai.szj@taobao.com>
      Signed-off-by: default avatarQiang Huang <h.huangqiang@huawei.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
      Cc: Jeff Liu <jeff.liu@oracle.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6de5a8bf
    • Sha Zhengju's avatar
      memcg: correct RESOURCE_MAX to ULLONG_MAX · 34ff8dc0
      Sha Zhengju authored
      
      
      Current RESOURCE_MAX is ULONG_MAX, but the value we used to set resource
      limit is unsigned long long, so we can set bigger value than that which is
      strange.  The XXX_MAX should be reasonable max value, bigger than that
      should be overflow.
      
      Notice that this change will affect user output of default *.limit_in_bytes:
      before change:
      
        $ cat /cgroup/memory/memory.limit_in_bytes
        9223372036854775807
      
      after change:
      
        $ cat /cgroup/memory/memory.limit_in_bytes
        18446744073709551615
      
      But it doesn't alter the API in term of input - we can still use "echo -1
      > *.limit_in_bytes" to reset the numbers to "unlimited".
      Signed-off-by: default avatarSha Zhengju <handai.szj@taobao.com>
      Signed-off-by: default avatarQiang Huang <h.huangqiang@huawei.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
      Cc: Jeff Liu <jeff.liu@oracle.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      34ff8dc0
    • Johannes Weiner's avatar
      mm: memcg: do not trap chargers with full callstack on OOM · 3812c8c8
      Johannes Weiner authored
      
      
      The memcg OOM handling is incredibly fragile and can deadlock.  When a
      task fails to charge memory, it invokes the OOM killer and loops right
      there in the charge code until it succeeds.  Comparably, any other task
      that enters the charge path at this point will go to a waitqueue right
      then and there and sleep until the OOM situation is resolved.  The problem
      is that these tasks may hold filesystem locks and the mmap_sem; locks that
      the selected OOM victim may need to exit.
      
      For example, in one reported case, the task invoking the OOM killer was
      about to charge a page cache page during a write(), which holds the
      i_mutex.  The OOM killer selected a task that was just entering truncate()
      and trying to acquire the i_mutex:
      
      OOM invoking task:
        mem_cgroup_handle_oom+0x241/0x3b0
        mem_cgroup_cache_charge+0xbe/0xe0
        add_to_page_cache_locked+0x4c/0x140
        add_to_page_cache_lru+0x22/0x50
        grab_cache_page_write_begin+0x8b/0xe0
        ext3_write_begin+0x88/0x270
        generic_file_buffered_write+0x116/0x290
        __generic_file_aio_write+0x27c/0x480
        generic_file_aio_write+0x76/0xf0           # takes ->i_mutex
        do_sync_write+0xea/0x130
        vfs_write+0xf3/0x1f0
        sys_write+0x51/0x90
        system_call_fastpath+0x18/0x1d
      
      OOM kill victim:
        do_truncate+0x58/0xa0              # takes i_mutex
        do_last+0x250/0xa30
        path_openat+0xd7/0x440
        do_filp_open+0x49/0xa0
        do_sys_open+0x106/0x240
        sys_open+0x20/0x30
        system_call_fastpath+0x18/0x1d
      
      The OOM handling task will retry the charge indefinitely while the OOM
      killed task is not releasing any resources.
      
      A similar scenario can happen when the kernel OOM killer for a memcg is
      disabled and a userspace task is in charge of resolving OOM situations.
      In this case, ALL tasks that enter the OOM path will be made to sleep on
      the OOM waitqueue and wait for userspace to free resources or increase
      the group's limit.  But a userspace OOM handler is prone to deadlock
      itself on the locks held by the waiting tasks.  For example one of the
      sleeping tasks may be stuck in a brk() call with the mmap_sem held for
      writing but the userspace handler, in order to pick an optimal victim,
      may need to read files from /proc/<pid>, which tries to acquire the same
      mmap_sem for reading and deadlocks.
      
      This patch changes the way tasks behave after detecting a memcg OOM and
      makes sure nobody loops or sleeps with locks held:
      
      1. When OOMing in a user fault, invoke the OOM killer and restart the
         fault instead of looping on the charge attempt.  This way, the OOM
         victim can not get stuck on locks the looping task may hold.
      
      2. When OOMing in a user fault but somebody else is handling it
         (either the kernel OOM killer or a userspace handler), don't go to
         sleep in the charge context.  Instead, remember the OOMing memcg in
         the task struct and then fully unwind the page fault stack with
         -ENOMEM.  pagefault_out_of_memory() will then call back into the
         memcg code to check if the -ENOMEM came from the memcg, and then
         either put the task to sleep on the memcg's OOM waitqueue or just
         restart the fault.  The OOM victim can no longer get stuck on any
         lock a sleeping task may hold.
      
      Debugged by Michal Hocko.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Reported-by: default avatarazurIt <azurit@pobox.sk>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: David Rientjes <rientjes@google.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3812c8c8
    • Johannes Weiner's avatar
      mm: memcg: rework and document OOM waiting and wakeup · fb2a6fc5
      Johannes Weiner authored
      
      
      The memcg OOM handler open-codes a sleeping lock for OOM serialization
      (trylock, wait, repeat) because the required locking is so specific to
      memcg hierarchies.  However, it would be nice if this construct would be
      clearly recognizable and not be as obfuscated as it is right now.  Clean
      up as follows:
      
      1. Remove the return value of mem_cgroup_oom_unlock()
      
      2. Rename mem_cgroup_oom_lock() to mem_cgroup_oom_trylock().
      
      3. Pull the prepare_to_wait() out of the memcg_oom_lock scope.  This
         makes it more obvious that the task has to be on the waitqueue
         before attempting to OOM-trylock the hierarchy, to not miss any
         wakeups before going to sleep.  It just didn't matter until now
         because it was all lumped together into the global memcg_oom_lock
         spinlock section.
      
      4. Pull the mem_cgroup_oom_notify() out of the memcg_oom_lock scope.
         It is proctected by the hierarchical OOM-lock.
      
      5. The memcg_oom_lock spinlock is only required to propagate the OOM
         lock in any given hierarchy atomically.  Restrict its scope to
         mem_cgroup_oom_(trylock|unlock).
      
      6. Do not wake up the waitqueue unconditionally at the end of the
         function.  Only the lockholder has to wake up the next in line
         after releasing the lock.
      
         Note that the lockholder kicks off the OOM-killer, which in turn
         leads to wakeups from the uncharges of the exiting task.  But a
         contender is not guaranteed to see them if it enters the OOM path
         after the OOM kills but before the lockholder releases the lock.
         Thus there has to be an explicit wakeup after releasing the lock.
      
      7. Put the OOM task on the waitqueue before marking the hierarchy as
         under OOM as that is the point where we start to receive wakeups.
         No point in listening before being on the waitqueue.
      
      8. Likewise, unmark the hierarchy before finishing the sleep, for
         symmetry.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: David Rientjes <rientjes@google.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: azurIt <azurit@pobox.sk>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      fb2a6fc5
    • Johannes Weiner's avatar
      mm: memcg: enable memcg OOM killer only for user faults · 519e5247
      Johannes Weiner authored
      
      
      System calls and kernel faults (uaccess, gup) can handle an out of memory
      situation gracefully and just return -ENOMEM.
      
      Enable the memcg OOM killer only for user faults, where it's really the
      only option available.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: David Rientjes <rientjes@google.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: azurIt <azurit@pobox.sk>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      519e5247
    • Johannes Weiner's avatar
      x86: finish user fault error path with fatal signal · 3a13c4d7
      Johannes Weiner authored
      
      
      The x86 fault handler bails in the middle of error handling when the
      task has a fatal signal pending.  For a subsequent patch this is a
      problem in OOM situations because it relies on pagefault_out_of_memory()
      being called even when the task has been killed, to perform proper
      per-task OOM state unwinding.
      
      Shortcutting the fault like this is a rather minor optimization that
      saves a few instructions in rare cases.  Just remove it for
      user-triggered faults.
      
      Use the opportunity to split the fault retry handling from actual fault
      errors and add locking documentation that reads suprisingly similar to
      ARM's.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: azurIt <azurit@pobox.sk>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3a13c4d7
    • Johannes Weiner's avatar
      arch: mm: pass userspace fault flag to generic fault handler · 759496ba
      Johannes Weiner authored
      
      
      Unlike global OOM handling, memory cgroup code will invoke the OOM killer
      in any OOM situation because it has no way of telling faults occuring in
      kernel context - which could be handled more gracefully - from
      user-triggered faults.
      
      Pass a flag that identifies faults originating in user space from the
      architecture-specific fault handlers to generic code so that memcg OOM
      handling can be improved.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: David Rientjes <rientjes@google.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: azurIt <azurit@pobox.sk>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      759496ba
    • Johannes Weiner's avatar
      arch: mm: do not invoke OOM killer on kernel fault OOM · 87134102
      Johannes Weiner authored
      
      
      Kernel faults are expected to handle OOM conditions gracefully (gup,
      uaccess etc.), so they should never invoke the OOM killer.  Reserve this
      for faults triggered in user context when it is the only option.
      
      Most architectures already do this, fix up the remaining few.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: azurIt <azurit@pobox.sk>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      87134102
    • Johannes Weiner's avatar
      arch: mm: remove obsolete init OOM protection · 94bce453
      Johannes Weiner authored
      The memcg code can trap tasks in the context of the failing allocation
      until an OOM situation is resolved.  They can hold all kinds of locks
      (fs, mm) at this point, which makes it prone to deadlocking.
      
      This series converts memcg OOM handling into a two step process that is
      started in the charge context, but any waiting is done after the fault
      stack is fully unwound.
      
      Patches 1-4 prepare architecture handlers to support the new memcg
      requirements, but in doing so they also remove old cruft and unify
      out-of-memory behavior across architectures.
      
      Patch 5 disables the memcg OOM handling for syscalls, readahead, kernel
      faults, because they can gracefully unwind the stack with -ENOMEM.  OOM
      handling is restricted to user triggered faults that have no other
      option.
      
      Patch 6 reworks memcg's hierarchical OOM locking to make it a little
      more obvious wth is going on in there: reduce locked regions, rename
      locking functions, reorder and document.
      
      Patch 7 implements the two-part OOM handling such that tasks are never
      trapped with the full charge stack in an OOM situation.
      
      This patch:
      
      Back before smart OOM killing, when faulting tasks were killed directly on
      allocation failures, the arch-specific fault handlers needed special
      protection for the init process.
      
      Now that all fault handlers call into the generic OOM killer (see commit
      609838cf
      
      : "mm: invoke oom-killer from remaining unconverted page
      fault handlers"), which already provides init protection, the
      arch-specific leftovers can be removed.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: azurIt <azurit@pobox.sk>
      Acked-by: Vineet Gupta <vgupta@synopsys.com>	[arch/arc bits]
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      94bce453
    • Andrew Morton's avatar
      memcg: trivial cleanups · f894ffa8
      Andrew Morton authored
      
      
      Clean up some mess made by the "Soft limit rework" series, and a few other
      things.
      
      Cc: Michal Hocko <mhocko@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f894ffa8
    • Michal Hocko's avatar
      memcg, vmscan: do not fall into reclaim-all pass too quickly · e975de99
      Michal Hocko authored
      
      
      shrink_zone starts with soft reclaim pass first and then falls back to
      regular reclaim if nothing has been scanned.  This behavior is natural
      but there is a catch.  Memcg iterators, when used with the reclaim
      cookie, are designed to help to prevent from over reclaim by
      interleaving reclaimers (per node-zone-priority) so the tree walk might
      miss many (even all) nodes in the hierarchy e.g.  when there are direct
      reclaimers racing with each other or with kswapd in the global case or
      multiple allocators reaching the limit for the target reclaim case.  To
      make it even more complicated, targeted reclaim doesn't do the whole
      tree walk because it stops reclaiming once it reclaims sufficient pages.
      As a result groups over the limit might be missed, thus nothing is
      scanned, and reclaim would fall back to the reclaim all mode.
      
      This patch checks for the incomplete tree walk in shrink_zone.  If no
      group has been visited and the hierarchy is soft reclaimable then we
      must have missed some groups, in which case the __shrink_zone is called
      again.  This doesn't guarantee there will be some progress of course
      because the current reclaimer might be still racing with others but it
      would at least give a chance to start the walk without a big risk of
      reclaim latencies.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: Balbir Singh <bsingharora@gmail.com>
      Cc: Glauber Costa <glommer@openvz.org>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Michel Lespinasse <walken@google.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Ying Han <yinghan@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e975de99
    • Michal Hocko's avatar
      memcg: track all children over limit in the root · 1be171d6
      Michal Hocko authored
      
      
      Children in soft limit excess are currently tracked up the hierarchy in
      memcg->children_in_excess.  Nevertheless there still might exist tons of
      groups that are not in hierarchy relation to the root cgroup (e.g.  all
      first level groups if root_mem_cgroup->use_hierarchy == false).
      
      As the whole tree walk has to be done when the iteration starts at
      root_mem_cgroup the iterator should be able to skip the walk if there is
      no child above the limit without iterating them.  This can be done
      easily if the root tracks all children rather than only hierarchical
      children.  This is done by this patch which updates root_mem_cgroup
      children_in_excess if root_mem_cgroup->use_hierarchy == false so the
      root knows about all children in excess.
      
      Please note that this is not an issue for inner memcgs which have
      use_hierarchy == false because then only the single group is visited so
      no special optimization is necessary.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: Balbir Singh <bsingharora@gmail.com>
      Cc: Glauber Costa <glommer@openvz.org>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Michel Lespinasse <walken@google.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Ying Han <yinghan@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1be171d6
    • Michal Hocko's avatar
      memcg, vmscan: do not attempt soft limit reclaim if it would not scan anything · e839b6a1
      Michal Hocko authored
      
      
      mem_cgroup_should_soft_reclaim controls whether soft reclaim pass is
      done and it always says yes currently.  Memcg iterators are clever to
      skip nodes that are not soft reclaimable quite efficiently but
      mem_cgroup_should_soft_reclaim can be more clever and do not start the
      soft reclaim pass at all if it knows that nothing would be scanned
      anyway.
      
      In order to do that, simply reuse mem_cgroup_soft_reclaim_eligible for
      the target group of the reclaim and allow the pass only if the whole
      subtree wouldn't be skipped.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: Balbir Singh <bsingharora@gmail.com>
      Cc: Glauber Costa <glommer@openvz.org>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Michel Lespinasse <walken@google.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Ying Han <yinghan@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e839b6a1
    • Michal Hocko's avatar
      memcg: track children in soft limit excess to improve soft limit · 7d910c05
      Michal Hocko authored
      
      
      Soft limit reclaim has to check the whole reclaim hierarchy while doing
      the first pass of the reclaim.  This leads to a higher system time which
      can be visible especially when there are many groups in the hierarchy.
      
      This patch adds a per-memcg counter of children in excess.  It also
      restores MEM_CGROUP_TARGET_SOFTLIMIT into mem_cgroup_event_ratelimit for a
      proper batching.
      
      If a group crosses soft limit for the first time it increases parent's
      children_in_excess up the hierarchy.  The similarly if a group gets below
      the limit it will decrease the counter.  The transition phase is recorded
      in soft_contributed flag.
      
      mem_cgroup_soft_reclaim_eligible then uses this information to better
      decide whether to skip the node or the whole subtree.  The rule is simple.
       Skip the node with a children in excess or skip the whole subtree
      otherwise.
      
      This has been tested by a stream IO (dd if=/dev/zero of=file with
      4*MemTotal size) which is quite sensitive to overhead during reclaim.  The
      load is running in a group with soft limit set to 0 and without any limit.
       Apart from that there was a hierarchy with ~500, 2k and 8k groups (two
      groups on each level) without any pages in them.  base denotes to the
      kernel on which the whole series is based on, rework is the kernel before
      this patch and reworkoptim is with this patch applied:
      
      * Run with soft limit set to 0
      Elapsed
      0-0-limit/base: min: 88.21 max: 94.61 avg: 91.73 std: 2.65 runs: 3
      0-0-limit/rework: min: 76.05 [86.2%] max: 79.08 [83.6%] avg: 77.84 [84.9%] std: 1.30 runs: 3
      0-0-limit/reworkoptim: min: 77.98 [88.4%] max: 80.36 [84.9%] avg: 78.92 [86.0%] std: 1.03 runs: 3
      System
      0.5k-0-limit/base: min: 34.86 max: 36.42 avg: 35.89 std: 0.73 runs: 3
      0.5k-0-limit/rework: min: 43.26 [124.1%] max: 48.95 [134.4%] avg: 46.09 [128.4%] std: 2.32 runs: 3
      0.5k-0-limit/reworkoptim: min: 46.98 [134.8%] max: 50.98 [140.0%] avg: 48.49 [135.1%] std: 1.77 runs: 3
      Elapsed
      0.5k-0-limit/base: min: 88.50 max: 97.52 avg: 93.92 std: 3.90 runs: 3
      0.5k-0-limit/rework: min: 75.92 [85.8%] max: 78.45 [80.4%] avg: 77.34 [82.3%] std: 1.06 runs: 3
      0.5k-0-limit/reworkoptim: min: 75.79 [85.6%] max: 79.37 [81.4%] avg: 77.55 [82.6%] std: 1.46 runs: 3
      System
      2k-0-limit/base: min: 34.57 max: 37.65 avg: 36.34 std: 1.30 runs: 3
      2k-0-limit/rework: min: 64.17 [185.6%] max: 68.20 [181.1%] avg: 66.21 [182.2%] std: 1.65 runs: 3
      2k-0-limit/reworkoptim: min: 49.78 [144.0%] max: 52.99 [140.7%] avg: 51.00 [140.3%] std: 1.42 runs: 3
      Elapsed
      2k-0-limit/base: min: 92.61 max: 97.83 avg: 95.03 std: 2.15 runs: 3
      2k-0-limit/rework: min: 78.33 [84.6%] max: 84.08 [85.9%] avg: 81.09 [85.3%] std: 2.35 runs: 3
      2k-0-limit/reworkoptim: min: 75.72 [81.8%] max: 78.57 [80.3%] avg: 76.73 [80.7%] std: 1.30 runs: 3
      System
      8k-0-limit/base: min: 39.78 max: 42.09 avg: 41.09 std: 0.97 runs: 3
      8k-0-limit/rework: min: 200.86 [504.9%] max: 265.42 [630.6%] avg: 241.80 [588.5%] std: 29.06 runs: 3
      8k-0-limit/reworkoptim: min: 53.70 [135.0%] max: 54.89 [130.4%] avg: 54.43 [132.5%] std: 0.52 runs: 3
      Elapsed
      8k-0-limit/base: min: 95.11 max: 98.61 avg: 96.81 std: 1.43 runs: 3
      8k-0-limit/rework: min: 246.96 [259.7%] max: 331.47 [336.1%] avg: 301.32 [311.2%] std: 38.52 runs: 3
      8k-0-limit/reworkoptim: min: 76.79 [80.7%] max: 81.71 [82.9%] avg: 78.97 [81.6%] std: 2.05 runs: 3
      
      System time is increased by 30-40% but it is reduced a lot comparing to
      kernel without this patch.  The higher time can be explained by the fact
      that the original soft reclaim scanned at priority 0 so it was much more
      effective for this workload (which is basically touch once and writeback).
       The Elapsed time looks better though (~20%).
      
      * Run with no soft limit set
      System
      0-no-limit/base: min: 42.18 max: 50.38 avg: 46.44 std: 3.36 runs: 3
      0-no-limit/rework: min: 40.57 [96.2%] max: 47.04 [93.4%] avg: 43.82 [94.4%] std: 2.64 runs: 3
      0-no-limit/reworkoptim: min: 40.45 [95.9%] max: 45.28 [89.9%] avg: 42.10 [90.7%] std: 2.25 runs: 3
      Elapsed
      0-no-limit/base: min: 75.97 max: 78.21 avg: 76.87 std: 0.96 runs: 3
      0-no-limit/rework: min: 75.59 [99.5%] max: 80.73 [103.2%] avg: 77.64 [101.0%] std: 2.23 runs: 3
      0-no-limit/reworkoptim: min: 77.85 [102.5%] max: 82.42 [105.4%] avg: 79.64 [103.6%] std: 1.99 runs: 3
      System
      0.5k-no-limit/base: min: 44.54 max: 46.93 avg: 46.12 std: 1.12 runs: 3
      0.5k-no-limit/rework: min: 42.09 [94.5%] max: 46.16 [98.4%] avg: 43.92 [95.2%] std: 1.69 runs: 3
      0.5k-no-limit/reworkoptim: min: 42.47 [95.4%] max: 45.67 [97.3%] avg: 44.06 [95.5%] std: 1.31 runs: 3
      Elapsed
      0.5k-no-limit/base: min: 78.26 max: 81.49 avg: 79.65 std: 1.36 runs: 3
      0.5k-no-limit/rework: min: 77.01 [98.4%] max: 80.43 [98.7%] avg: 78.30 [98.3%] std: 1.52 runs: 3
      0.5k-no-limit/reworkoptim: min: 76.13 [97.3%] max: 77.87 [95.6%] avg: 77.18 [96.9%] std: 0.75 runs: 3
      System
      2k-no-limit/base: min: 62.96 max: 69.14 avg: 66.14 std: 2.53 runs: 3
      2k-no-limit/rework: min: 76.01 [120.7%] max: 81.06 [117.2%] avg: 78.17 [118.2%] std: 2.12 runs: 3
      2k-no-limit/reworkoptim: min: 62.57 [99.4%] max: 66.10 [95.6%] avg: 64.53 [97.6%] std: 1.47 runs: 3
      Elapsed
      2k-no-limit/base: min: 76.47 max: 84.22 avg: 79.12 std: 3.60 runs: 3
      2k-no-limit/rework: min: 89.67 [117.3%] max: 93.26 [110.7%] avg: 91.10 [115.1%] std: 1.55 runs: 3
      2k-no-limit/reworkoptim: min: 76.94 [100.6%] max: 79.21 [94.1%] avg: 78.45 [99.2%] std: 1.07 runs: 3
      System
      8k-no-limit/base: min: 104.74 max: 151.34 avg: 129.21 std: 19.10 runs: 3
      8k-no-limit/rework: min: 205.23 [195.9%] max: 285.94 [188.9%] avg: 258.98 [200.4%] std: 38.01 runs: 3
      8k-no-limit/reworkoptim: min: 161.16 [153.9%] max: 184.54 [121.9%] avg: 174.52 [135.1%] std: 9.83 runs: 3
      Elapsed
      8k-no-limit/base: min: 125.43 max: 181.00 avg: 154.81 std: 22.80 runs: 3
      8k-no-limit/rework: min: 254.05 [202.5%] max: 355.67 [196.5%] avg: 321.46 [207.6%] std: 47.67 runs: 3
      8k-no-limit/reworkoptim: min: 193.77 [154.5%] max: 222.72 [123.0%] avg: 210.18 [135.8%] std: 12.13 runs: 3
      
      Both System and Elapsed are in stdev with the base kernel for all
      configurations except for 8k where both System and Elapsed are up by 35%.
      I do not have a good explanation for this because there is no soft reclaim
      pass going on as no group is above the limit which is checked in
      mem_cgroup_should_soft_reclaim.
      
      Then I have tested kernel build with the same configuration to see the
      behavior with a more general behavior.
      
      * Soft limit set to 0 for the build
      System
      0-0-limit/base: min: 242.70 max: 245.17 avg: 243.85 std: 1.02 runs: 3
      0-0-limit/rework min: 237.86 [98.0%] max: 240.22 [98.0%] avg: 239.00 [98.0%] std: 0.97 runs: 3
      0-0-limit/reworkoptim: min: 241.11 [99.3%] max: 243.53 [99.3%] avg: 242.01 [99.2%] std: 1.08 runs: 3
      Elapsed
      0-0-limit/base: min: 348.48 max: 360.86 avg: 356.04 std: 5.41 runs: 3
      0-0-limit/rework min: 286.95 [82.3%] max: 290.26 [80.4%] avg: 288.27 [81.0%] std: 1.43 runs: 3
      0-0-limit/reworkoptim: min: 286.55 [82.2%] max: 289.00 [80.1%] avg: 287.69 [80.8%] std: 1.01 runs: 3
      System
      0.5k-0-limit/base: min: 251.77 max: 254.41 avg: 252.70 std: 1.21 runs: 3
      0.5k-0-limit/rework min: 286.44 [113.8%] max: 289.30 [113.7%] avg: 287.60 [113.8%] std: 1.23 runs: 3
      0.5k-0-limit/reworkoptim: min: 252.18 [100.2%] max: 253.16 [99.5%] avg: 252.62 [100.0%] std: 0.41 runs: 3
      Elapsed
      0.5k-0-limit/base: min: 347.83 max: 353.06 avg: 350.04 std: 2.21 runs: 3
      0.5k-0-limit/rework min: 290.19 [83.4%] max: 295.62 [83.7%] avg: 293.12 [83.7%] std: 2.24 runs: 3
      0.5k-0-limit/reworkoptim: min: 293.91 [84.5%] max: 294.87 [83.5%] avg: 294.29 [84.1%] std: 0.42 runs: 3
      System
      2k-0-limit/base: min: 263.05 max: 271.52 avg: 267.94 std: 3.58 runs: 3
      2k-0-limit/rework min: 458.99 [174.5%] max: 468.31 [172.5%] avg: 464.45 [173.3%] std: 3.97 runs: 3
      2k-0-limit/reworkoptim: min: 267.10 [101.5%] max: 279.38 [102.9%] avg: 272.78 [101.8%] std: 5.05 runs: 3
      Elapsed
      2k-0-limit/base: min: 372.33 max: 379.32 avg: 375.47 std: 2.90 runs: 3
      2k-0-limit/rework min: 334.40 [89.8%] max: 339.52 [89.5%] avg: 337.44 [89.9%] std: 2.20 runs: 3
      2k-0-limit/reworkoptim: min: 301.47 [81.0%] max: 319.19 [84.1%] avg: 307.90 [82.0%] std: 8.01 runs: 3
      System
      8k-0-limit/base: min: 320.50 max: 332.10 avg: 325.46 std: 4.88 runs: 3
      8k-0-limit/rework min: 1115.76 [348.1%] max: 1165.66 [351.0%] avg: 1132.65 [348.0%] std: 23.34 runs: 3
      8k-0-limit/reworkoptim: min: 403.75 [126.0%] max: 409.22 [123.2%] avg: 406.16 [124.8%] std: 2.28 runs: 3
      Elapsed
      8k-0-limit/base: min: 475.48 max: 585.19 avg: 525.54 std: 45.30 runs: 3
      8k-0-limit/rework min: 616.25 [129.6%] max: 625.90 [107.0%] avg: 620.68 [118.1%] std: 3.98 runs: 3
      8k-0-limit/reworkoptim: min: 420.18 [88.4%] max: 428.28 [73.2%] avg: 423.05 [80.5%] std: 3.71 runs: 3
      
      Apart from 8k the system time is comparable with the base kernel while
      Elapsed is up to 20% better with all configurations.
      
      * No soft limit set
      System
      0-no-limit/base: min: 234.76 max: 237.42 avg: 236.25 std: 1.11 runs: 3
      0-no-limit/rework min: 233.09 [99.3%] max: 238.65 [100.5%] avg: 236.09 [99.9%] std: 2.29 runs: 3
      0-no-limit/reworkoptim: min: 236.12 [100.6%] max: 240.53 [101.3%] avg: 237.94 [100.7%] std: 1.88 runs: 3
      Elapsed
      0-no-limit/base: min: 288.52 max: 295.42 avg: 291.29 std: 2.98 runs: 3
      0-no-limit/rework min: 283.17 [98.1%] max: 284.33 [96.2%] avg: 283.78 [97.4%] std: 0.48 runs: 3
      0-no-limit/reworkoptim: min: 288.50 [100.0%] max: 290.79 [98.4%] avg: 289.78 [99.5%] std: 0.95 runs: 3
      System
      0.5k-no-limit/base: min: 286.51 max: 293.23 avg: 290.21 std: 2.78 runs: 3
      0.5k-no-limit/rework min: 291.69 [101.8%] max: 294.38 [100.4%] avg: 292.97 [101.0%] std: 1.10 runs: 3
      0.5k-no-limit/reworkoptim: min: 277.05 [96.7%] max: 288.76 [98.5%] avg: 284.17 [97.9%] std: 5.11 runs: 3
      Elapsed
      0.5k-no-limit/base: min: 294.94 max: 298.92 avg: 296.47 std: 1.75 runs: 3
      0.5k-no-limit/rework min: 292.55 [99.2%] max: 294.21 [98.4%] avg: 293.55 [99.0%] std: 0.72 runs: 3
      0.5k-no-limit/reworkoptim: min: 294.41 [99.8%] max: 301.67 [100.9%] avg: 297.78 [100.4%] std: 2.99 runs: 3
      System
      2k-no-limit/base: min: 443.41 max: 466.66 avg: 457.66 std: 10.19 runs: 3
      2k-no-limit/rework min: 490.11 [110.5%] max: 516.02 [110.6%] avg: 501.42 [109.6%] std: 10.83 runs: 3
      2k-no-limit/reworkoptim: min: 435.25 [98.2%] max: 458.11 [98.2%] avg: 446.73 [97.6%] std: 9.33 runs: 3
      Elapsed
      2k-no-limit/base: min: 330.85 max: 333.75 avg: 332.52 std: 1.23 runs: 3
      2k-no-limit/rework min: 343.06 [103.7%] max: 349.59 [104.7%] avg: 345.95 [104.0%] std: 2.72 runs: 3
      2k-no-limit/reworkoptim: min: 330.01 [99.7%] max: 333.92 [100.1%] avg: 332.22 [99.9%] std: 1.64 runs: 3
      System
      8k-no-limit/base: min: 1175.64 max: 1259.38 avg: 1222.39 std: 34.88 runs: 3
      8k-no-limit/rework min: 1226.31 [104.3%] max: 1241.60 [98.6%] avg: 1233.74 [100.9%] std: 6.25 runs: 3
      8k-no-limit/reworkoptim: min: 1023.45 [87.1%] max: 1056.74 [83.9%] avg: 1038.92 [85.0%] std: 13.69 runs: 3
      Elapsed
      8k-no-limit/base: min: 613.36 max: 619.60 avg: 616.47 std: 2.55 runs: 3
      8k-no-limit/rework min: 627.56 [102.3%] max: 642.33 [103.7%] avg: 633.44 [102.8%] std: 6.39 runs: 3
      8k-no-limit/reworkoptim: min: 545.89 [89.0%] max: 555.36 [89.6%] avg: 552.06 [89.6%] std: 4.37 runs: 3
      
      and these numbers look good as well.  System time is around 100%
      (suprisingly better for the 8k case) and Elapsed is copies that trend.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: Balbir Singh <bsingharora@gmail.com>
      Cc: Glauber Costa <glommer@openvz.org>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Michel Lespinasse <walken@google.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Ying Han <yinghan@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7d910c05
    • Michal Hocko's avatar
      memcg: enhance memcg iterator to support predicates · de57780d
      Michal Hocko authored
      
      
      The caller of the iterator might know that some nodes or even subtrees
      should be skipped but there is no way to tell iterators about that so the
      only choice left is to let iterators to visit each node and do the
      selection outside of the iterating code.  This, however, doesn't scale
      well with hierarchies with many groups where only few groups are
      interesting.
      
      This patch adds mem_cgroup_iter_cond variant of the iterator with a
      callback which gets called for every visited node.  There are three
      possible ways how the callback can influence the walk.  Either the node is
      visited, it is skipped but the tree walk continues down the tree or the
      whole subtree of the current group is skipped.
      
      [hughd@google.com: fix memcg-less page reclaim]
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: Balbir Singh <bsingharora@gmail.com>
      Cc: Glauber Costa <glommer@openvz.org>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Michel Lespinasse <walken@google.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Ying Han <yinghan@google.com>
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      de57780d
    • Michal Hocko's avatar
      vmscan, memcg: do softlimit reclaim also for targeted reclaim · a5b7c87f
      Michal Hocko authored
      
      
      Soft reclaim has been done only for the global reclaim (both background
      and direct).  Since "memcg: integrate soft reclaim tighter with zone
      shrinking code" there is no reason for this limitation anymore as the soft
      limit reclaim doesn't use any special code paths and it is a part of the
      zone shrinking code which is used by both global and targeted reclaims.
      
      From the semantic point of view it is natural to consider soft limit
      before touching all groups in the hierarchy tree which is touching the
      hard limit because soft limit tells us where to push back when there is a
      memory pressure.  It is not important whether the pressure comes from the
      limit or imbalanced zones.
      
      This patch simply enables soft reclaim unconditionally in
      mem_cgroup_should_soft_reclaim so it is enabled for both global and
      targeted reclaim paths.  mem_cgroup_soft_reclaim_eligible needs to learn
      about the root of the reclaim to know where to stop checking soft limit
      state of parents up the hierarchy.  Say we have
      
      A (over soft limit)
       \
        B (below s.l., hit the hard limit)
       / \
      C   D (below s.l.)
      
      B is the source of the outside memory pressure now for D but we shouldn't
      soft reclaim it because it is behaving well under B subtree and we can
      still reclaim from C (pressumably it is over the limit).
      mem_cgroup_soft_reclaim_eligible should therefore stop climbing up the
      hierarchy at B (root of the memory pressure).
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Reviewed-by: default avatarGlauber Costa <glommer@openvz.org>
      Reviewed-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Balbir Singh <bsingharora@gmail.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Michel Lespinasse <walken@google.com>
      Cc: Ying Han <yinghan@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a5b7c87f
    • Michal Hocko's avatar
      memcg: get rid of soft-limit tree infrastructure · e883110a
      Michal Hocko authored
      
      
      Now that the soft limit is integrated to the reclaim directly the whole
      soft-limit tree infrastructure is not needed anymore.  Rip it out.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Reviewed-by: default avatarGlauber Costa <glommer@openvz.org>
      Reviewed-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Balbir Singh <bsingharora@gmail.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Michel Lespinasse <walken@google.com>
      Cc: Ying Han <yinghan@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e883110a
    • Michal Hocko's avatar
      memcg, vmscan: integrate soft reclaim tighter with zone shrinking code · 3b38722e
      Michal Hocko authored
      This patchset is sitting out of tree for quite some time without any
      objections.  I would be really happy if it made it into 3.12.  I do not
      want to push it too hard but I think this work is basically ready and
      waiting more doesn't help.
      
      The basic idea is quite simple.  Pull soft reclaim into shrink_zone in the
      first step and get rid of the previous soft reclaim infrastructure.
      shrink_zone is done in two passes now.  First it tries to do the soft
      limit reclaim and it falls back to reclaim-all mode if no group is over
      the limit or no pages have been scanned.  The second pass happens at the
      same priority so the only time we waste is the memcg tree walk which has
      been updated in the third step to have only negligible overhead.
      
      As a bonus we will get rid of a _lot_ of code by this and soft reclaim
      will not stand out like before when it wasn't integrated into the zone
      shrinking code and it reclaimed at priority 0 (the testing results show
      that some workloads suffers from such an aggressive reclaim).  The clean
      up is in a separate patch because I felt it would be easier to review that
      way.
      
      The second step is soft limit reclaim integration into targeted reclaim.
      It should be rather straight forward.  Soft limit has been used only for
      the global reclaim so far but it makes sense for any kind of pressure
      coming from up-the-hierarchy, including targeted reclaim.
      
      The third step (patches 4-8) addresses the tree walk overhead by enhancing
      memcg iterators to enable skipping whole subtrees and tracking number of
      over soft limit children at each level of the hierarchy.  This information
      is updated same way the old soft limit tree was updated (from
      memcg_check_events) so we shouldn't see an additional overhead.  In fact
      mem_cgroup_update_soft_limit is much simpler than tree manipulation done
      previously.
      
      __shrink_zone uses mem_cgroup_soft_reclaim_eligible as a predicate for
      mem_cgroup_iter so the decision whether a particular group should be
      visited is done at the iterator level which allows us to decide to skip
      the whole subtree as well (if there is no child in excess).  This reduces
      the tree walk overhead considerably.
      
      * TEST 1
      ========
      
      My primary test case was a parallel kernel build with 2 groups (make is
      running with -j8 with a distribution .config in a separate cgroup without
      any hard limit) on a 32 CPU machine booted with 1GB memory and both builds
      run taskset to Node 0 cpus.
      
      I was mostly interested in 2 setups.  Default - no soft limit set and -
      and 0 soft limit set to both groups.  The first one should tell us whether
      the rework regresses the default behavior while the second one should show
      us improvements in an extreme case where both workloads are always over
      the soft limit.
      
      /usr/bin/time -v has been used to collect the statistics and each
      configuration had 3 runs after fresh boot without any other load on the
      system.
      
      base is mmotm-2013-07-18-16-40
      rework all 8 patches applied on top of base
      
      * No-limit
      User
      no-limit/base: min: 651.92 max: 672.65 avg: 664.33 std: 8.01 runs: 6
      no-limit/rework: min: 657.34 [100.8%] max: 668.39 [99.4%] avg: 663.13 [99.8%] std: 3.61 runs: 6
      System
      no-limit/base: min: 69.33 max: 71.39 avg: 70.32 std: 0.79 runs: 6
      no-limit/rework: min: 69.12 [99.7%] max: 71.05 [99.5%] avg: 70.04 [99.6%] std: 0.59 runs: 6
      Elapsed
      no-limit/base: min: 398.27 max: 422.36 avg: 408.85 std: 7.74 runs: 6
      no-limit/rework: min: 386.36 [97.0%] max: 438.40 [103.8%] avg: 416.34 [101.8%] std: 18.85 runs: 6
      
      The results are within noise. Elapsed time has a bigger variance but the
      average looks good.
      
      * 0-limit
      User
      0-limit/base: min: 573.76 max: 605.63 avg: 585.73 std: 12.21 runs: 6
      0-limit/rework: min: 645.77 [112.6%] max: 666.25 [110.0%] avg: 656.97 [112.2%] std: 7.77 runs: 6
      System
      0-limit/base: min: 69.57 max: 71.13 avg: 70.29 std: 0.54 runs: 6
      0-limit/rework: min: 68.68 [98.7%] max: 71.40 [100.4%] avg: 69.91 [99.5%] std: 0.87 runs: 6
      Elapsed
      0-limit/base: min: 1306.14 max: 1550.17 avg: 1430.35 std: 90.86 runs: 6
      0-limit/rework: min: 404.06 [30.9%] max: 465.94 [30.1%] avg: 434.81 [30.4%] std: 22.68 runs: 6
      
      The improvement is really huge here (even bigger than with my previous
      testing and I suspect that this highly depends on the storage).  Page
      fault statistics tell us at least part of the story:
      
      Minor
      0-limit/base: min: 37180461.00 max: 37319986.00 avg: 37247470.00 std: 54772.71 runs: 6
      0-limit/rework: min: 36751685.00 [98.8%] max: 36805379.00 [98.6%] avg: 36774506.33 [98.7%] std: 17109.03 runs: 6
      Major
      0-limit/base: min: 170604.00 max: 221141.00 avg: 196081.83 std: 18217.01 runs: 6
      0-limit/rework: min: 2864.00 [1.7%] max: 10029.00 [4.5%] avg: 5627.33 [2.9%] std: 2252.71 runs: 6
      
      Same as with my previous testing Minor faults are more or less within
      noise but Major fault count is way bellow the base kernel.
      
      While this looks as a nice win it is fair to say that 0-limit
      configuration is quite artificial. So I was playing with 0-no-limit
      loads as well.
      
      * TEST 2
      ========
      
      The following results are from 2 groups configuration on a 16GB machine
      (single NUMA node).
      
      - A running stream IO (dd if=/dev/zero of=local.file bs=1024) with
        2*TotalMem with 0 soft limit.
      - B running a mem_eater which consumes TotalMem-1G without any limit. The
        mem_eater consumes the memory in 100 chunks with 1s nap after each
        mmap+poppulate so that both loads have chance to fight for the memory.
      
      The expected result is that B shouldn't be reclaimed and A shouldn't see
      a big dropdown in elapsed time.
      
      User
      base: min: 2.68 max: 2.89 avg: 2.76 std: 0.09 runs: 3
      rework: min: 3.27 [122.0%] max: 3.74 [129.4%] avg: 3.44 [124.6%] std: 0.21 runs: 3
      System
      base: min: 86.26 max: 88.29 avg: 87.28 std: 0.83 runs: 3
      rework: min: 81.05 [94.0%] max: 84.96 [96.2%] avg: 83.14 [95.3%] std: 1.61 runs: 3
      Elapsed
      base: min: 317.28 max: 332.39 avg: 325.84 std: 6.33 runs: 3
      rework: min: 281.53 [88.7%] max: 298.16 [89.7%] avg: 290.99 [89.3%] std: 6.98 runs: 3
      
      System time improved slightly as well as Elapsed. My previous testing
      has shown worse numbers but this again seem to depend on the storage
      speed.
      
      My theory is that the writeback doesn't catch up and prio-0 soft reclaim
      falls into wait on writeback page too often in the base kernel. The
      patched kernel doesn't do that because the soft reclaim is done from the
      kswapd/direct reclaim context. This can be seen on the following graph
      nicely. The A's group usage_in_bytes regurarly drops really low very often.
      
      All 3 runs
      http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/stream.png
      resp. a detail of the single run
      http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/stream-one-run.png
      
      mem_eater seems to be doing better as well. It gets to the full
      allocation size faster as can be seen on the following graph:
      http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/mem_eater-one-run.png
      
      /proc/meminfo collected during the test also shows that rework kernel
      hasn't swapped that much (well almost not at all):
      base: max: 123900 K avg: 56388.29 K
      rework: max: 300 K avg: 128.68 K
      
      kswapd and direct reclaim statistics are of no use unfortunatelly because
      soft reclaim is not accounted properly as the counters are hidden by
      global_reclaim() checks in the base kernel.
      
      * TEST 3
      ========
      
      Another test was the same configuration as TEST2 except the stream IO was
      replaced by a single kbuild (16 parallel jobs bound to Node0 cpus same as
      in TEST1) and mem_eater allocated TotalMem-200M so kbuild had only 200MB
      left.
      
      Kbuild did better with the rework kernel here as well:
      User
      base: min: 860.28 max: 872.86 avg: 868.03 std: 5.54 runs: 3
      rework: min: 880.81 [102.4%] max: 887.45 [101.7%] avg: 883.56 [101.8%] std: 2.83 runs: 3
      System
      base: min: 84.35 max: 85.06 avg: 84.79 std: 0.31 runs: 3
      rework: min: 85.62 [101.5%] max: 86.09 [101.2%] avg: 85.79 [101.2%] std: 0.21 runs: 3
      Elapsed
      base: min: 135.36 max: 243.30 avg: 182.47 std: 45.12 runs: 3
      rework: min: 110.46 [81.6%] max: 116.20 [47.8%] avg: 114.15 [62.6%] std: 2.61 runs: 3
      Minor
      base: min: 36635476.00 max: 36673365.00 avg: 36654812.00 std: 15478.03 runs: 3
      rework: min: 36639301.00 [100.0%] max: 36695541.00 [100.1%] avg: 36665511.00 [100.0%] std: 23118.23 runs: 3
      Major
      base: min: 14708.00 max: 53328.00 avg: 31379.00 std: 16202.24 runs: 3
      rework: min: 302.00 [2.1%] max: 414.00 [0.8%] avg: 366.33 [1.2%] std: 47.22 runs: 3
      
      Again we can see a significant improvement in Elapsed (it also seems to
      be more stable), there is a huge dropdown for the Major page faults and
      much more swapping:
      base: max: 583736 K avg: 112547.43 K
      rework: max: 4012 K avg: 124.36 K
      
      Graphs from all three runs show the variability of the kbuild quite
      nicely.  It even seems that it took longer after every run with the base
      kernel which would be quite surprising as the source tree for the build is
      removed and caches are dropped after each run so the build operates on a
      freshly extracted sources everytime.
      http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/kbuild-mem_eater.png
      
      My other testing shows that this is just a matter of timing and other runs
      behave differently the std for Elapsed time is similar ~50.  Example of
      other three runs:
      http://labs.suse.cz/mhocko/soft_limit_rework/stream_io-vs-mem_eater/kbuild-mem_eater2.png
      
      
      
      So to wrap this up.  The series is still doing good and improves the soft
      limit.
      
      The testing results for bunch of cgroups with both stream IO and kbuild
      loads can be found in "memcg: track children in soft limit excess to
      improve soft limit".
      
      This patch:
      
      Memcg soft reclaim has been traditionally triggered from the global
      reclaim paths before calling shrink_zone.  mem_cgroup_soft_limit_reclaim
      then picked up a group which exceeds the soft limit the most and reclaimed
      it with 0 priority to reclaim at least SWAP_CLUSTER_MAX pages.
      
      The infrastructure requires per-node-zone trees which hold over-limit
      groups and keep them up-to-date (via memcg_check_events) which is not cost
      free.  Although this overhead hasn't turned out to be a bottle neck the
      implementation is suboptimal because mem_cgroup_update_tree has no idea
      which zones consumed memory over the limit so we could easily end up
      having a group on a node-zone tree having only few pages from that
      node-zone.
      
      This patch doesn't try to fix node-zone trees management because it seems
      that integrating soft reclaim into zone shrinking sounds much easier and
      more appropriate for several reasons.  First of all 0 priority reclaim was
      a crude hack which might lead to big stalls if the group's LRUs are big
      and hard to reclaim (e.g.  a lot of dirty/writeback pages).  Soft reclaim
      should be applicable also to the targeted reclaim which is awkward right
      now without additional hacks.  Last but not least the whole infrastructure
      eats quite some code.
      
      After this patch shrink_zone is done in 2 passes.  First it tries to do
      the soft reclaim if appropriate (only for global reclaim for now to keep
      compatible with the original state) and fall back to ignoring soft limit
      if no group is eligible to soft reclaim or nothing has been scanned during
      the first pass.  Only groups which are over their soft limit or any of
      their parents up the hierarchy is over the limit are considered eligible
      during the first pass.
      
      Soft limit tree which is not necessary anymore will be removed in the
      follow up patch to make this patch smaller and easier to review.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Reviewed-by: default avatarGlauber Costa <glommer@openvz.org>
      Reviewed-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Ying Han <yinghan@google.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Michel Lespinasse <walken@google.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Balbir Singh <bsingharora@gmail.com>
      Cc: Glauber Costa <glommer@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3b38722e
    • Li Zefan's avatar
      memcg: remove redundant code in mem_cgroup_force_empty_write() · c33bd835
      Li Zefan authored
      
      
      vfs guarantees the cgroup won't be destroyed, so it's redundant to get a
      css reference.
      Signed-off-by: default avatarLi Zefan <lizefan@huawei.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Tejun Heo <tj@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c33bd835