From: Howard McLauchlan <hmclauchlan@xxxxxx>
Subject: mm: make should_failslab always available for fault injection
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@xxxxxx
Signed-off-by: Howard McLauchlan <hmclauchlan@xxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Josef Bacik <jbacik@xxxxxx>
Cc: Johannes Weiner <jweiner@xxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/fault-inject.h | 5 +++--
mm/failslab.c | 2 +-
mm/slab_common.c | 8 ++++++++
3 files changed, 12 insertions(+), 3 deletions(-)
diff -puN include/linux/fault-inject.h~mm-make-should_failslab-always-available-for-fault-injection include/linux/fault-inject.h
--- a/include/linux/fault-inject.h~mm-make-should_failslab-always-available-for-fault-injection
+++ a/include/linux/fault-inject.h
@@ -64,10 +64,11 @@ static inline struct dentry *fault_creat
struct kmem_cache;
+int should_failslab(struct kmem_cache *s, gfp_t gfpflags);
#ifdef CONFIG_FAILSLAB
-extern bool should_failslab(struct kmem_cache *s, gfp_t gfpflags);
+extern bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags);
#else
-static inline bool should_failslab(struct kmem_cache *s, gfp_t gfpflags)
+static inline bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags)
{
return false;
}
diff -puN mm/failslab.c~mm-make-should_failslab-always-available-for-fault-injection mm/failslab.c
--- a/mm/failslab.c~mm-make-should_failslab-always-available-for-fault-injection
+++ a/mm/failslab.c
@@ -14,7 +14,7 @@ static struct {
.cache_filter = false,
};
-bool should_failslab(struct kmem_cache *s, gfp_t gfpflags)
+bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags)
{
/* No fault-injection for bootstrap cache */
if (unlikely(s == kmem_cache))
diff -puN mm/slab_common.c~mm-make-should_failslab-always-available-for-fault-injection mm/slab_common.c
--- a/mm/slab_common.c~mm-make-should_failslab-always-available-for-fault-injection
+++ a/mm/slab_common.c
@@ -1516,3 +1516,11 @@ EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
EXPORT_TRACEPOINT_SYMBOL(kfree);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
+
+int should_failslab(struct kmem_cache *s, gfp_t gfpflags)
+{
+ if (__should_failslab(s, gfpflags))
+ return -ENOMEM;
+ return 0;
+}
+ALLOW_ERROR_INJECTION(should_failslab, ERRNO);
_
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
