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Subject[PATCH 30/31] Fix use of uninitialized variable in cache_grow()
Date
From: Miklos Szeredi <mszeredi@suse.cz>

This fixes a bug in reserve-slub.patch.

If cache_grow() was called with objp != NULL then the 'reserve' local
variable wasn't initialized. This resulted in ac->reserve being set to
a rubbish value. Due to this in some circumstances huge amounts of
slab pages were allocated (due to slab_force_alloc() returning true),
which caused atomic page allocation failures and slowdown of the
system.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
---
mm/slab.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

Index: mmotm/mm/slab.c
===================================================================
--- mmotm.orig/mm/slab.c
+++ mmotm/mm/slab.c
@@ -2760,7 +2760,7 @@ static int cache_grow(struct kmem_cache
size_t offset;
gfp_t local_flags;
struct kmem_list3 *l3;
- int reserve;
+ int reserve = -1;

/*
* Be lazy and only check for valid flags here, keeping it out of the
@@ -2816,7 +2816,8 @@ static int cache_grow(struct kmem_cache
if (local_flags & __GFP_WAIT)
local_irq_disable();
check_irq_off();
- slab_set_reserve(cachep, reserve);
+ if (reserve != -1)
+ slab_set_reserve(cachep, reserve);
spin_lock(&l3->list_lock);

/* Make slab active. */

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