From 4f6923fbb352d126659cabe34806cff75c7b5ea0 Mon Sep 17 00:00:00 2001 From: Howard McLauchlan Date: Thu, 5 Apr 2018 16:23:57 -0700 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 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 Reviewed-by: Andrew Morton Cc: Akinobu Mita Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Josef Bacik Cc: Johannes Weiner Cc: Alexei Starovoitov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slab_common.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'mm/slab_common.c') diff --git a/mm/slab_common.c b/mm/slab_common.c index 2e682a4c8877..98dcdc352062 100644 --- a/mm/slab_common.c +++ b/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); -- cgit v1.2.3