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author | 2014-02-10 14:25:46 -0800 | |
---|---|---|
committer | 2014-02-10 16:01:42 -0800 | |
commit | 1e4dd9461fabfbc780cdfaf103cec790f3a53325 (patch) | |
tree | 5842f997753a45cdc3e6c937d852f17056c34d70 /mm | |
parent | gitignore: add all.config (diff) | |
download | linux-1e4dd9461fab.tar.gz linux-1e4dd9461fab.tar.bz2 linux-1e4dd9461fab.zip |
slub: do not assert not having lock in removing freed partial
Vladimir reported the following issue:
Commit c65c1877bd68 ("slub: use lockdep_assert_held") requires
remove_partial() to be called with n->list_lock held, but free_partial()
called from kmem_cache_close() on cache destruction does not follow this
rule, leading to a warning:
WARNING: CPU: 0 PID: 2787 at mm/slub.c:1536 __kmem_cache_shutdown+0x1b2/0x1f0()
Modules linked in:
CPU: 0 PID: 2787 Comm: modprobe Tainted: G W 3.14.0-rc1-mm1+ #1
Hardware name:
0000000000000600 ffff88003ae1dde8 ffffffff816d9583 0000000000000600
0000000000000000 ffff88003ae1de28 ffffffff8107c107 0000000000000000
ffff880037ab2b00 ffff88007c240d30 ffffea0001ee5280 ffffea0001ee52a0
Call Trace:
__kmem_cache_shutdown+0x1b2/0x1f0
kmem_cache_destroy+0x43/0xf0
xfs_destroy_zones+0x103/0x110 [xfs]
exit_xfs_fs+0x38/0x4e4 [xfs]
SyS_delete_module+0x19a/0x1f0
system_call_fastpath+0x16/0x1b
His solution was to add a spinlock in order to quiet lockdep. Although
there would be no contention to adding the lock, that lock also requires
disabling of interrupts which will have a larger impact on the system.
Instead of adding a spinlock to a location where it is not needed for
lockdep, make a __remove_partial() function that does not test if the
list_lock is held, as no one should have it due to it being freed.
Also added a __add_partial() function that does not do the lock
validation either, as it is not needed for the creation of the cache.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Vladimir Davydov <vdavydov@parallels.com>
Suggested-by: David Rientjes <rientjes@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@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/slub.c | 32 |
1 files changed, 20 insertions, 12 deletions
diff --git a/mm/slub.c b/mm/slub.c index 3d3a8a7a0f8c..25f14ad8f817 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1518,11 +1518,9 @@ static void discard_slab(struct kmem_cache *s, struct page *page) /* * Management of partially allocated slabs. */ -static inline void add_partial(struct kmem_cache_node *n, - struct page *page, int tail) +static inline void +__add_partial(struct kmem_cache_node *n, struct page *page, int tail) { - lockdep_assert_held(&n->list_lock); - n->nr_partial++; if (tail == DEACTIVATE_TO_TAIL) list_add_tail(&page->lru, &n->partial); @@ -1530,15 +1528,27 @@ static inline void add_partial(struct kmem_cache_node *n, list_add(&page->lru, &n->partial); } -static inline void remove_partial(struct kmem_cache_node *n, - struct page *page) +static inline void add_partial(struct kmem_cache_node *n, + struct page *page, int tail) { lockdep_assert_held(&n->list_lock); + __add_partial(n, page, tail); +} +static inline void +__remove_partial(struct kmem_cache_node *n, struct page *page) +{ list_del(&page->lru); n->nr_partial--; } +static inline void remove_partial(struct kmem_cache_node *n, + struct page *page) +{ + lockdep_assert_held(&n->list_lock); + __remove_partial(n, page); +} + /* * Remove slab from the partial list, freeze it and * return the pointer to the freelist. @@ -2904,12 +2914,10 @@ static void early_kmem_cache_node_alloc(int node) inc_slabs_node(kmem_cache_node, node, page->objects); /* - * the lock is for lockdep's sake, not for any actual - * race protection + * No locks need to be taken here as it has just been + * initialized and there is no concurrent access. */ - spin_lock(&n->list_lock); - add_partial(n, page, DEACTIVATE_TO_HEAD); - spin_unlock(&n->list_lock); + __add_partial(n, page, DEACTIVATE_TO_HEAD); } static void free_kmem_cache_nodes(struct kmem_cache *s) @@ -3195,7 +3203,7 @@ static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n) list_for_each_entry_safe(page, h, &n->partial, lru) { if (!page->inuse) { - remove_partial(n, page); + __remove_partial(n, page); discard_slab(s, page); } else { list_slab_objects(s, page, |