Subject: [merged] slub-do-not-assert-not-having-lock-in-removing-freed-partial.patch removed from -mm tree
To: rostedt@xxxxxxxxxxx,cl@xxxxxxxxx,penberg@xxxxxxxxxx,rientjes@xxxxxxxxxx,vdavydov@xxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 11 Feb 2014 11:23:42 -0800
The patch titled
Subject: slub: do not assert not having lock in removing freed partial
has been removed from the -mm tree. Its filename was
slub-do-not-assert-not-having-lock-in-removing-freed-partial.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Steven Rostedt <rostedt@xxxxxxxxxxx>
Subject: 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:
[<ffffffff816d9583>] dump_stack+0x51/0x6e
[<ffffffff8107c107>] warn_slowpath_common+0x87/0xb0
[<ffffffff8107c145>] warn_slowpath_null+0x15/0x20
[<ffffffff811c7fe2>] __kmem_cache_shutdown+0x1b2/0x1f0
[<ffffffff811908d3>] kmem_cache_destroy+0x43/0xf0
[<ffffffffa013a123>] xfs_destroy_zones+0x103/0x110 [xfs]
[<ffffffffa0192b54>] exit_xfs_fs+0x38/0x4e4 [xfs]
[<ffffffff811036fa>] SyS_delete_module+0x19a/0x1f0
[<ffffffff816dfcd8>] ? retint_swapgs+0x13/0x1b
[<ffffffff810d2125>] ? trace_hardirqs_on_caller+0x105/0x1d0
[<ffffffff81359efe>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff816e8539>] 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@xxxxxxxxxxx>
Reported-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Suggested-by: David Rientjes <rientjes@xxxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Acked-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 32 ++++++++++++++++++++------------
1 file changed, 20 insertions(+), 12 deletions(-)
diff -puN mm/slub.c~slub-do-not-assert-not-having-lock-in-removing-freed-partial mm/slub.c
--- a/mm/slub.c~slub-do-not-assert-not-having-lock-in-removing-freed-partial
+++ a/mm/slub.c
@@ -1518,11 +1518,9 @@ static void discard_slab(struct kmem_cac
/*
* 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 km
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(
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_cac
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,
_
Patches currently in -mm which might be from rostedt@xxxxxxxxxxx are
origin.patch
lib-devresc-fix-some-sparse-warnings.patch
linux-next.patch
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