• Hugh Dickins's avatar
    shmem: fix init_page_accessed use to stop !PageLRU bug · 66d2f4d2
    Hugh Dickins authored
    Under shmem swapping load, I sometimes hit the VM_BUG_ON_PAGE(!PageLRU)
    in isolate_lru_pages() at mm/vmscan.c:1281!
    Commit 2457aec6 ("mm: non-atomically mark page accessed during page
    cache allocation where possible") looks like interrupted work-in-progress.
    mm/filemap.c's call to init_page_accessed() is fine, but not mm/shmem.c's
    - shmem_write_begin() is clearly wrong to use it after shmem_getpage(),
    when the page is always visible in radix_tree, and often already on LRU.
    Revert change to shmem_write_begin(), and use init_page_accessed() or
    mark_page_accessed() appropriately for SGP_WRITE in shmem_getpage_gfp().
    SGP_WRITE also covers shmem_symlink(), which did not mark_page_accessed()
    before; but since many other filesystems use [__]page_symlink(), which did
    and does mark the page accessed, consider this as rectifying an oversight.
    Signed-off-by: default avatarHugh Dickins <hughd@google.com>
    Acked-by: default avatarMel Gorman <mgorman@suse.de>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Vlastimil Babka <vbabka@suse.cz>
    Cc: Michal Hocko <mhocko@suse.cz>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: Prabhakar Lad <prabhakar.csengg@gmail.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
shmem.c 78.3 KB