• Dmitry Safonov's avatar
    mm: slab: free kmem_cache_node after destroy sysfs file · 52b4b950
    Dmitry Safonov authored
    When slub_debug alloc_calls_show is enabled we will try to track
    location and user of slab object on each online node, kmem_cache_node
    structure and cpu_cache/cpu_slub shouldn't be freed till there is the
    last reference to sysfs file.
    
    This fixes the following panic:
    
       BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
       IP:  list_locations+0x169/0x4e0
       PGD 257304067 PUD 438456067 PMD 0
       Oops: 0000 [#1] SMP
       CPU: 3 PID: 973074 Comm: cat ve: 0 Not tainted 3.10.0-229.7.2.ovz.9.30-00007-japdoll-dirty #2 9.30
       Hardware name: DEPO Computers To Be Filled By O.E.M./H67DE3, BIOS L1.60c 07/14/2011
       task: ffff88042a5dc5b0 ti: ffff88037f8d8000 task.ti: ffff88037f8d8000
       RIP: list_locations+0x169/0x4e0
       Call Trace:
         alloc_calls_show+0x1d/0x30
         slab_attr_show+0x1b/0x30
         sysfs_read_file+0x9a/0x1a0
         vfs_read+0x9c/0x170
         SyS_read+0x58/0xb0
         system_call_fastpath+0x16/0x1b
       Code: 5e 07 12 00 b9 00 04 00 00 3d 00 04 00 00 0f 4f c1 3d 00 04 00 00 89 45 b0 0f 84 c3 00 00 00 48 63 45 b0 49 8b 9c c4 f8 00 00 00 <48> 8b 43 20 48 85 c0 74 b6 48 89 df e8 46 37 44 00 48 8b 53 10
       CR2: 0000000000000020
    
    Separated __kmem_cache_release from __kmem_cache_shutdown which now
    called on slab_kmem_cache_release (after the last reference to sysfs
    file object has dropped).
    
    Reintroduced locking in free_partial as sysfs file might access cache's
    partial list after shutdowning - partial revert of the commit
    69cb8e6b ("slub: free slabs without holding locks").  Zap
    __remove_partial and use remove_partial (w/o underscores) as
    free_partial now takes list_lock which s partial revert for commit
    1e4dd946
    
     ("slub: do not assert not having lock in removing freed
    partial")
    Signed-off-by: default avatarDmitry Safonov <dsafonov@virtuozzo.com>
    Suggested-by: default avatarVladimir Davydov <vdavydov@virtuozzo.com>
    Acked-by: default avatarVladimir Davydov <vdavydov@virtuozzo.com>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: Pekka Enberg <penberg@kernel.org>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    52b4b950