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  1. Jan 21, 2011
  2. Jan 20, 2011
    • Linus Torvalds's avatar
      Merge branch 'core-fixes-for-linus' of... · 2b1caf6e
      Linus Torvalds authored
      Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
      
      * 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
        smp: Allow on_each_cpu() to be called while early_boot_irqs_disabled status to init/main.c
        lockdep: Move early boot local IRQ enable/disable status to init/main.c
      2b1caf6e
    • Rafael J. Wysocki's avatar
      ACPI / PM: Call suspend_nvs_free() earlier during resume · d551d81d
      Rafael J. Wysocki authored
      
      It turns out that some device drivers map pages from the ACPI NVS region
      during resume using ioremap(), which conflicts with ioremap_cache() used
      for mapping those pages by the NVS save/restore code in nvs.c.
      
      Make the NVS pages mapped by the code in nvs.c be unmapped before device
      drivers' resume routines run.
      
      Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d551d81d
    • Rafael J. Wysocki's avatar
      ACPI: Introduce acpi_os_ioremap() · 2d6d9fd3
      Rafael J. Wysocki authored
      
      Commit ca9b600b ("ACPI / PM: Make suspend_nvs_save() use
      acpi_os_map_memory()") attempted to prevent the code in osl.c and nvs.c
      from using different ioremap() variants by making the latter use
      acpi_os_map_memory() for mapping the NVS pages.  However, that also
      requires acpi_os_unmap_memory() to be used for unmapping them, which
      causes synchronize_rcu() to be executed many times in a row
      unnecessarily and introduces substantial delays during resume on some
      systems.
      
      Instead of using acpi_os_map_memory() for mapping the NVS pages in nvs.c
      introduce acpi_os_ioremap() calling ioremap_cache() and make the code in
      both osl.c and nvs.c use it.
      
      Reported-by: default avatarJeff Chua <jeff.chua.linux@gmail.com>
      Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2d6d9fd3
    • Linus Torvalds's avatar
      Merge branch 'akpm' · 8d99641f
      Linus Torvalds authored
      * akpm:
        kernel/smp.c: consolidate writes in smp_call_function_interrupt()
        kernel/smp.c: fix smp_call_function_many() SMP race
        memcg: correctly order reading PCG_USED and pc->mem_cgroup
        backlight: fix 88pm860x_bl macro collision
        drivers/leds/ledtrig-gpio.c: make output match input, tighten input checking
        MAINTAINERS: update Atmel AT91 entry
        mm: fix truncate_setsize() comment
        memcg: fix rmdir, force_empty with THP
        memcg: fix LRU accounting with THP
        memcg: fix USED bit handling at uncharge in THP
        memcg: modify accounting function for supporting THP better
        fs/direct-io.c: don't try to allocate more than BIO_MAX_PAGES in a bio
        mm: compaction: prevent division-by-zero during user-requested compaction
        mm/vmscan.c: remove duplicate include of compaction.h
        memblock: fix memblock_is_region_memory()
        thp: keep highpte mapped until it is no longer needed
        kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT
      8d99641f
    • Milton Miller's avatar
      kernel/smp.c: consolidate writes in smp_call_function_interrupt() · 225c8e01
      Milton Miller authored
      
      We have to test the cpu mask in the interrupt handler before checking the
      refs, otherwise we can start to follow an entry before its deleted and
      find it partially initailzed for the next trip.  Presently we also clear
      the cpumask bit before executing the called function, which implies
      getting write access to the line.  After the function is called we then
      decrement refs, and if they go to zero we then unlock the structure.
      
      However, this implies getting write access to the call function data
      before and after another the function is called.  If we can assert that no
      smp_call_function execution function is allowed to enable interrupts, then
      we can move both writes to after the function is called, hopfully allowing
      both writes with one cache line bounce.
      
      On a 256 thread system with a kernel compiled for 1024 threads, the time
      to execute testcase in the "smp_call_function_many race" changelog was
      reduced by about 30-40ms out of about 545 ms.
      
      I decided to keep this as WARN because its now a buggy function, even
      though the stack trace is of no value -- a simple printk would give us the
      information needed.
      
      Raw data:
      
      Without patch:
        ipi_test startup took 1219366ns complete 539819014ns total 541038380ns
        ipi_test startup took 1695754ns complete 543439872ns total 545135626ns
        ipi_test startup took 7513568ns complete 539606362ns total 547119930ns
        ipi_test startup took 13304064ns complete 533898562ns total 547202626ns
        ipi_test startup took 8668192ns complete 544264074ns total 552932266ns
        ipi_test startup took 4977626ns complete 548862684ns total 553840310ns
        ipi_test startup took 2144486ns complete 541292318ns total 543436804ns
        ipi_test startup took 21245824ns complete 530280180ns total 551526004ns
      
      With patch:
        ipi_test startup took 5961748ns complete 500859628ns total 506821376ns
        ipi_test startup took 8975996ns complete 495098924ns total 504074920ns
        ipi_test startup took 19797750ns complete 492204740ns total 512002490ns
        ipi_test startup took 14824796ns complete 487495878ns total 502320674ns
        ipi_test startup took 11514882ns complete 494439372ns total 505954254ns
        ipi_test startup took 8288084ns complete 502570774ns total 510858858ns
        ipi_test startup took 6789954ns complete 493388112ns total 500178066ns
      
      	#include <linux/module.h>
      	#include <linux/init.h>
      	#include <linux/sched.h> /* sched clock */
      
      	#define ITERATIONS 100
      
      	static void do_nothing_ipi(void *dummy)
      	{
      	}
      
      	static void do_ipis(struct work_struct *dummy)
      	{
      		int i;
      
      		for (i = 0; i < ITERATIONS; i++)
      			smp_call_function(do_nothing_ipi, NULL, 1);
      
      		printk(KERN_DEBUG "cpu %d finished\n", smp_processor_id());
      	}
      
      	static struct work_struct work[NR_CPUS];
      
      	static int __init testcase_init(void)
      	{
      		int cpu;
      		u64 start, started, done;
      
      		start = local_clock();
      		for_each_online_cpu(cpu) {
      			INIT_WORK(&work[cpu], do_ipis);
      			schedule_work_on(cpu, &work[cpu]);
      		}
      		started = local_clock();
      		for_each_online_cpu(cpu)
      			flush_work(&work[cpu]);
      		done = local_clock();
      		pr_info("ipi_test startup took %lldns complete %lldns total %lldns\n",
      			started-start, done-started, done-start);
      
      		return 0;
      	}
      
      	static void __exit testcase_exit(void)
      	{
      	}
      
      	module_init(testcase_init)
      	module_exit(testcase_exit)
      	MODULE_LICENSE("GPL");
      	MODULE_AUTHOR("Anton Blanchard");
      
      Signed-off-by: default avatarMilton Miller <miltonm@bga.com>
      Cc: Anton Blanchard <anton@samba.org>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      225c8e01
    • Anton Blanchard's avatar
      kernel/smp.c: fix smp_call_function_many() SMP race · 6dc19899
      Anton Blanchard authored
      
      I noticed a failure where we hit the following WARN_ON in
      generic_smp_call_function_interrupt:
      
                      if (!cpumask_test_and_clear_cpu(cpu, data->cpumask))
                              continue;
      
                      data->csd.func(data->csd.info);
      
                      refs = atomic_dec_return(&data->refs);
                      WARN_ON(refs < 0);      <-------------------------
      
      We atomically tested and cleared our bit in the cpumask, and yet the
      number of cpus left (ie refs) was 0.  How can this be?
      
      It turns out commit 54fdade1
      ("generic-ipi: make struct call_function_data lockless") is at fault.  It
      removes locking from smp_call_function_many and in doing so creates a
      rather complicated race.
      
      The problem comes about because:
      
       - The smp_call_function_many interrupt handler walks call_function.queue
         without any locking.
       - We reuse a percpu data structure in smp_call_function_many.
       - We do not wait for any RCU grace period before starting the next
         smp_call_function_many.
      
      Imagine a scenario where CPU A does two smp_call_functions back to back,
      and CPU B does an smp_call_function in between.  We concentrate on how CPU
      C handles the calls:
      
      CPU A            CPU B                  CPU C              CPU D
      
      smp_call_function
                                              smp_call_function_interrupt
                                                  walks
      					call_function.queue sees
      					data from CPU A on list
      
                       smp_call_function
      
                                              smp_call_function_interrupt
                                                  walks
      
                                              call_function.queue sees
                                                (stale) CPU A on list
      							   smp_call_function int
      							   clears last ref on A
      							   list_del_rcu, unlock
      smp_call_function reuses
      percpu *data A
                                               data->cpumask sees and
                                               clears bit in cpumask
                                               might be using old or new fn!
                                               decrements refs below 0
      
      set data->refs (too late!)
      
      The important thing to note is since the interrupt handler walks a
      potentially stale call_function.queue without any locking, then another
      cpu can view the percpu *data structure at any time, even when the owner
      is in the process of initialising it.
      
      The following test case hits the WARN_ON 100% of the time on my PowerPC
      box (having 128 threads does help :)
      
      #include <linux/module.h>
      #include <linux/init.h>
      
      #define ITERATIONS 100
      
      static void do_nothing_ipi(void *dummy)
      {
      }
      
      static void do_ipis(struct work_struct *dummy)
      {
      	int i;
      
      	for (i = 0; i < ITERATIONS; i++)
      		smp_call_function(do_nothing_ipi, NULL, 1);
      
      	printk(KERN_DEBUG "cpu %d finished\n", smp_processor_id());
      }
      
      static struct work_struct work[NR_CPUS];
      
      static int __init testcase_init(void)
      {
      	int cpu;
      
      	for_each_online_cpu(cpu) {
      		INIT_WORK(&work[cpu], do_ipis);
      		schedule_work_on(cpu, &work[cpu]);
      	}
      
      	return 0;
      }
      
      static void __exit testcase_exit(void)
      {
      }
      
      module_init(testcase_init)
      module_exit(testcase_exit)
      MODULE_LICENSE("GPL");
      MODULE_AUTHOR("Anton Blanchard");
      
      I tried to fix it by ordering the read and the write of ->cpumask and
      ->refs.  In doing so I missed a critical case but Paul McKenney was able
      to spot my bug thankfully :) To ensure we arent viewing previous
      iterations the interrupt handler needs to read ->refs then ->cpumask then
      ->refs _again_.
      
      Thanks to Milton Miller and Paul McKenney for helping to debug this issue.
      
      [miltonm@bga.com: add WARN_ON and BUG_ON, remove extra read of refs before initial read of mask that doesn't help (also noted by Peter Zijlstra), adjust comments, hopefully clarify scenario ]
      [miltonm@bga.com: remove excess tests]
      Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
      Signed-off-by: default avatarMilton Miller <miltonm@bga.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: <stable@kernel.org> [2.6.32+]
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6dc19899
    • Johannes Weiner's avatar
      memcg: correctly order reading PCG_USED and pc->mem_cgroup · 713735b4
      Johannes Weiner authored
      
      The placement of the read-side barrier is confused: the writer first
      sets pc->mem_cgroup, then PCG_USED.  The read-side barrier has to be
      between testing PCG_USED and reading pc->mem_cgroup.
      
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Acked-by: default avatarDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
      Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      713735b4
    • Randy Dunlap's avatar
      backlight: fix 88pm860x_bl macro collision · 2550326a
      Randy Dunlap authored
      
      Fix collision with kernel-supplied #define:
      
        drivers/video/backlight/88pm860x_bl.c:24:1: warning: "CURRENT_MASK" redefined
        arch/x86/include/asm/page_64_types.h:6:1: warning: this is the location of the previous definition
      
      Signed-off-by: default avatarRandy Dunlap <randy.dunlap@oracle.com>
      Cc: Haojian Zhuang <haojian.zhuang@marvell.com>
      Cc: Richard Purdie <rpurdie@rpsys.net>
      Cc: <stable@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2550326a
    • Janusz Krzysztofik's avatar
      drivers/leds/ledtrig-gpio.c: make output match input, tighten input checking · cc587ece
      Janusz Krzysztofik authored
      
      Replicate changes made to drivers/leds/ledtrig-backlight.c.
      
      Cc: Paul Mundt <lethal@linux-sh.org>
      Cc: Richard Purdie <richard.purdie@linuxfoundation.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      cc587ece
    • Nicolas Ferre's avatar
      MAINTAINERS: update Atmel AT91 entry · c1fc8675
      Nicolas Ferre authored
      
      Add two co-maintainers and update the entry with new information.
      
      Signed-off-by: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
      Acked-by: default avatarAndrew Victor <linux@maxim.org.za>
      Acked-by: default avatarJean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
      Cc: Russell King <rmk@arm.linux.org.uk>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c1fc8675
    • Jan Kara's avatar
      mm: fix truncate_setsize() comment · 382e27da
      Jan Kara authored
      
      Contrary to what the comment says, truncate_setsize() should be called
      *before* filesystem truncated blocks.
      
      Signed-off-by: default avatarJan Kara <jack@suse.cz>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      382e27da
    • KAMEZAWA Hiroyuki's avatar
      memcg: fix rmdir, force_empty with THP · 987eba66
      KAMEZAWA Hiroyuki authored
      
      Now, when THP is enabled, memcg's rmdir() function is broken because
      move_account() for THP page is not supported.
      
      This will cause account leak or -EBUSY issue at rmdir().
      This patch fixes the issue by supporting move_account() THP pages.
      
      Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
      Cc: Balbir Singh <balbir@linux.vnet.ibm.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>
      987eba66
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