a9659476d4
When failslab was originally written, the intention of the
"ignore-gfp-wait" flag default value ("N") was to fail GFP_ATOMIC
allocations. Those were defined as (__GFP_HIGH), and the code would test
for __GFP_WAIT (0x10u).
However, since then, __GFP_WAIT was replaced by __GFP_RECLAIM
(___GFP_DIRECT_RECLAIM|___GFP_KSWAPD_RECLAIM), and GFP_ATOMIC is now
defined as (__GFP_HIGH|__GFP_ATOMIC|__GFP_KSWAPD_RECLAIM).
This means that when the flag is false, almost no allocation ever fails
(as even GFP_ATOMIC allocations contain ___GFP_KSWAPD_RECLAIM).
Restore the original intent of the code, by ignoring calls that directly
reclaim only (__GFP_DIRECT_RECLAIM), and thus, failing GFP_ATOMIC calls
again by default.
Link: http://lkml.kernel.org/r/20190520214514.81360-1-drinkcat@chromium.org
Fixes: 71baba4b92 ("mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM")
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
62 lines
1.4 KiB
C
62 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/fault-inject.h>
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#include <linux/slab.h>
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#include <linux/mm.h>
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#include "slab.h"
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static struct {
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struct fault_attr attr;
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bool ignore_gfp_reclaim;
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bool cache_filter;
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} failslab = {
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.attr = FAULT_ATTR_INITIALIZER,
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.ignore_gfp_reclaim = true,
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.cache_filter = false,
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};
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bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags)
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{
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/* No fault-injection for bootstrap cache */
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if (unlikely(s == kmem_cache))
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return false;
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if (gfpflags & __GFP_NOFAIL)
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return false;
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if (failslab.ignore_gfp_reclaim &&
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(gfpflags & __GFP_DIRECT_RECLAIM))
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return false;
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if (failslab.cache_filter && !(s->flags & SLAB_FAILSLAB))
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return false;
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return should_fail(&failslab.attr, s->object_size);
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}
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static int __init setup_failslab(char *str)
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{
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return setup_fault_attr(&failslab.attr, str);
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}
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__setup("failslab=", setup_failslab);
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#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
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static int __init failslab_debugfs_init(void)
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{
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struct dentry *dir;
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umode_t mode = S_IFREG | 0600;
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dir = fault_create_debugfs_attr("failslab", NULL, &failslab.attr);
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if (IS_ERR(dir))
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return PTR_ERR(dir);
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debugfs_create_bool("ignore-gfp-wait", mode, dir,
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&failslab.ignore_gfp_reclaim);
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debugfs_create_bool("cache-filter", mode, dir,
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&failslab.cache_filter);
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return 0;
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}
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late_initcall(failslab_debugfs_init);
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#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
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