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mm: fix unexpected changes to {failslab|fail_page_alloc}.attr

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When we specify __GFP_NOWARN, we only expect that no warnings will be
issued for current caller.  But in the __should_failslab() and
__should_fail_alloc_page(), the local GFP flags alter the global
{failslab|fail_page_alloc}.attr, which is persistent and shared by all
tasks.  This is not what we expected, let's fix it.

[akpm@linux-foundation.org: unexport should_fail_ex()]
Link: https://lkml.kernel.org/r/20221118100011.2634-1-zhengqi.arch@bytedance.com
Fixes: 3f913fc5f9 ("mm: fix missing handler for __GFP_NOWARN")
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Qi Zheng
2022-11-18 18:00:11 +08:00
committed by Andrew Morton
parent de1ccfb648
commit ea4452de2a
4 changed files with 28 additions and 11 deletions
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12
mm/failslab.c
View File

@@ -16,6 +16,8 @@ static struct {
bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags)
{
int flags = 0;
/* No fault-injection for bootstrap cache */
if (unlikely(s == kmem_cache))
return false;
@@ -30,10 +32,16 @@ bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags)
if (failslab.cache_filter && !(s->flags & SLAB_FAILSLAB))
return false;
/*
* In some cases, it expects to specify __GFP_NOWARN
* to avoid printing any information(not just a warning),
* thus avoiding deadlocks. See commit 6b9dbedbe349 for
* details.
*/
if (gfpflags & __GFP_NOWARN)
failslab.attr.no_warn = true;
flags |= FAULT_NOWARN;
return should_fail(&failslab.attr, s->object_size);
return should_fail_ex(&failslab.attr, s->object_size, flags);
}
static int __init setup_failslab(char *str)

7
mm/page_alloc.c
View File

@@ -3887,6 +3887,8 @@ __setup("fail_page_alloc=", setup_fail_page_alloc);
static bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
{
int flags = 0;
if (order < fail_page_alloc.min_order)
return false;
if (gfp_mask & __GFP_NOFAIL)
@@ -3897,10 +3899,11 @@ static bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
(gfp_mask & __GFP_DIRECT_RECLAIM))
return false;
/* See comment in __should_failslab() */
if (gfp_mask & __GFP_NOWARN)
fail_page_alloc.attr.no_warn = true;
flags |= FAULT_NOWARN;
return should_fail(&fail_page_alloc.attr, 1 << order);
return should_fail_ex(&fail_page_alloc.attr, 1 << order, flags);
}
#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS