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author | Mikulas Patocka <mpatocka@redhat.com> | 2018-06-28 08:26:09 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-06-28 20:16:44 +0200 |
commit | d50d82faa0c964e31f7a946ba8aba7c715ca7ab0 (patch) | |
tree | a8d5f022d9d35f9117373caf760e3d8791f24621 /mm | |
parent | Revert mm/vmstat.c: fix vmstat_update() preemption BUG (diff) | |
download | linux-d50d82faa0c964e31f7a946ba8aba7c715ca7ab0.tar.xz linux-d50d82faa0c964e31f7a946ba8aba7c715ca7ab0.zip |
slub: fix failure when we delete and create a slab cache
In kernel 4.17 I removed some code from dm-bufio that did slab cache
merging (commit 21bb13276768: "dm bufio: remove code that merges slab
caches") - both slab and slub support merging caches with identical
attributes, so dm-bufio now just calls kmem_cache_create and relies on
implicit merging.
This uncovered a bug in the slub subsystem - if we delete a cache and
immediatelly create another cache with the same attributes, it fails
because of duplicate filename in /sys/kernel/slab/. The slub subsystem
offloads freeing the cache to a workqueue - and if we create the new
cache before the workqueue runs, it complains because of duplicate
filename in sysfs.
This patch fixes the bug by moving the call of kobject_del from
sysfs_slab_remove_workfn to shutdown_cache. kobject_del must be called
while we hold slab_mutex - so that the sysfs entry is deleted before a
cache with the same attributes could be created.
Running device-mapper-test-suite with:
dmtest run --suite thin-provisioning -n /commit_failure_causes_fallback/
triggered:
Buffer I/O error on dev dm-0, logical block 1572848, async page read
device-mapper: thin: 253:1: metadata operation 'dm_pool_alloc_data_block' failed: error = -5
device-mapper: thin: 253:1: aborting current metadata transaction
sysfs: cannot create duplicate filename '/kernel/slab/:a-0000144'
CPU: 2 PID: 1037 Comm: kworker/u48:1 Not tainted 4.17.0.snitm+ #25
Hardware name: Supermicro SYS-1029P-WTR/X11DDW-L, BIOS 2.0a 12/06/2017
Workqueue: dm-thin do_worker [dm_thin_pool]
Call Trace:
dump_stack+0x5a/0x73
sysfs_warn_dup+0x58/0x70
sysfs_create_dir_ns+0x77/0x80
kobject_add_internal+0xba/0x2e0
kobject_init_and_add+0x70/0xb0
sysfs_slab_add+0xb1/0x250
__kmem_cache_create+0x116/0x150
create_cache+0xd9/0x1f0
kmem_cache_create_usercopy+0x1c1/0x250
kmem_cache_create+0x18/0x20
dm_bufio_client_create+0x1ae/0x410 [dm_bufio]
dm_block_manager_create+0x5e/0x90 [dm_persistent_data]
__create_persistent_data_objects+0x38/0x940 [dm_thin_pool]
dm_pool_abort_metadata+0x64/0x90 [dm_thin_pool]
metadata_operation_failed+0x59/0x100 [dm_thin_pool]
alloc_data_block.isra.53+0x86/0x180 [dm_thin_pool]
process_cell+0x2a3/0x550 [dm_thin_pool]
do_worker+0x28d/0x8f0 [dm_thin_pool]
process_one_work+0x171/0x370
worker_thread+0x49/0x3f0
kthread+0xf8/0x130
ret_from_fork+0x35/0x40
kobject_add_internal failed for :a-0000144 with -EEXIST, don't try to register things with the same name in the same directory.
kmem_cache_create(dm_bufio_buffer-16) failed with error -17
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1806151817130.6333@file01.intranet.prod.int.rdu2.redhat.com
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reported-by: Mike Snitzer <snitzer@redhat.com>
Tested-by: Mike Snitzer <snitzer@redhat.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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/slab_common.c | 4 | ||||
-rw-r--r-- | mm/slub.c | 7 |
2 files changed, 10 insertions, 1 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c index 890b1f04a03a..2296caf87bfb 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -567,10 +567,14 @@ static int shutdown_cache(struct kmem_cache *s) list_del(&s->list); if (s->flags & SLAB_TYPESAFE_BY_RCU) { +#ifdef SLAB_SUPPORTS_SYSFS + sysfs_slab_unlink(s); +#endif list_add_tail(&s->list, &slab_caches_to_rcu_destroy); schedule_work(&slab_caches_to_rcu_destroy_work); } else { #ifdef SLAB_SUPPORTS_SYSFS + sysfs_slab_unlink(s); sysfs_slab_release(s); #else slab_kmem_cache_release(s); diff --git a/mm/slub.c b/mm/slub.c index a3b8467c14af..51258eff4178 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5667,7 +5667,6 @@ static void sysfs_slab_remove_workfn(struct work_struct *work) kset_unregister(s->memcg_kset); #endif kobject_uevent(&s->kobj, KOBJ_REMOVE); - kobject_del(&s->kobj); out: kobject_put(&s->kobj); } @@ -5752,6 +5751,12 @@ static void sysfs_slab_remove(struct kmem_cache *s) schedule_work(&s->kobj_remove_work); } +void sysfs_slab_unlink(struct kmem_cache *s) +{ + if (slab_state >= FULL) + kobject_del(&s->kobj); +} + void sysfs_slab_release(struct kmem_cache *s) { if (slab_state >= FULL) |