4f6923fbb3
should_failslab() is a convenient function to hook into for directed
error injection into kmalloc(). However, it is only available if a
config flag is set.
The following BCC script, for example, fails kmalloc() calls after a
btrfs umount:
from bcc import BPF
prog = r"""
BPF_HASH(flag);
#include <linux/mm.h>
int kprobe__btrfs_close_devices(void *ctx) {
u64 key = 1;
flag.update(&key, &key);
return 0;
}
int kprobe__should_failslab(struct pt_regs *ctx) {
u64 key = 1;
u64 *res;
res = flag.lookup(&key);
if (res != 0) {
bpf_override_return(ctx, -ENOMEM);
}
return 0;
}
"""
b = BPF(text=prog)
while 1:
b.kprobe_poll()
This patch refactors the should_failslab implementation so that the
function is always available for error injection, independent of flags.
This change would be similar in nature to commit f5490d3ec921 ("block:
Add should_fail_bio() for bpf error injection").
Link: http://lkml.kernel.org/r/20180222020320.6944-1-hmclauchlan@fb.com
Signed-off-by: Howard McLauchlan <hmclauchlan@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
68 lines
1.5 KiB
C
68 lines
1.5 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 && (gfpflags & __GFP_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 | S_IRUSR | S_IWUSR;
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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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if (!debugfs_create_bool("ignore-gfp-wait", mode, dir,
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&failslab.ignore_gfp_reclaim))
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goto fail;
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if (!debugfs_create_bool("cache-filter", mode, dir,
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&failslab.cache_filter))
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goto fail;
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return 0;
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fail:
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debugfs_remove_recursive(dir);
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return -ENOMEM;
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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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