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authorVlastimil Babka <vbabka@suse.cz>2020-08-07 09:18:45 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-07 21:33:22 +0300
commit060807f841ac94d3826ce6fa3b4f3831cd0c015b (patch)
tree7fb9985e561e2d1ae304ca222c250ca9eab1654d /Documentation/vm
parent32a6f409b6935d175464f26d31250ea13fda6b66 (diff)
downloadlinux-060807f841ac94d3826ce6fa3b4f3831cd0c015b.tar.xz
mm, slub: make remaining slub_debug related attributes read-only
SLUB_DEBUG creates several files under /sys/kernel/slab/<cache>/ that can be read to check if the respective debugging options are enabled for given cache. Some options, namely sanity_checks, trace, and failslab can be also enabled and disabled at runtime by writing into the files. The runtime toggling is racy. Some options disable __CMPXCHG_DOUBLE when enabled, which means that in case of concurrent allocations, some can still use __CMPXCHG_DOUBLE and some not, leading to potential corruption. The s->flags field is also not updated or checked atomically. The simplest solution is to remove the runtime toggling. The extended slub_debug boot parameter syntax introduced by earlier patch should allow to fine-tune the debugging configuration during boot with same granularity. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Roman Gushchin <guro@fb.com> Cc: Christoph Lameter <cl@linux.com> Cc: Jann Horn <jannh@google.com> Cc: Vijayanand Jitta <vjitta@codeaurora.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Pekka Enberg <penberg@kernel.org> Link: http://lkml.kernel.org/r/20200610163135.17364-5-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/vm')
-rw-r--r--Documentation/vm/slub.rst7
1 files changed, 2 insertions, 5 deletions
diff --git a/Documentation/vm/slub.rst b/Documentation/vm/slub.rst
index 36241dfba024..289d231cee97 100644
--- a/Documentation/vm/slub.rst
+++ b/Documentation/vm/slub.rst
@@ -116,11 +116,8 @@ options from the ``slub_debug`` parameter translate to the following files::
T trace
A failslab
-The sanity_checks, trace and failslab files are writable, so writing 1 or 0
-will enable or disable the option at runtime. The writes to trace and failslab
-may return -EINVAL if the cache is subject to slab merging. Careful with
-tracing: It may spew out lots of information and never stop if used on the
-wrong slab.
+Careful with tracing: It may spew out lots of information and never stop if
+used on the wrong slab.
Slab merging
============