mm: fix unexpected changes to {failslab|fail_page_alloc}.attr

When we specify __GFP_NOWARN, we only expect that no warnings will be issued for current caller. But in the __should_failslab() and __should_fail_alloc_page(), the local GFP flags alter the global {failslab|fail_page_alloc}.attr, which is persistent and shared by all tasks. This is not what we expected, let's fix it. [akpm@linux-foundation.org: unexport should_fail_ex()] Link: https://lkml.kernel.org/r/20221118100011.2634-1-zhengqi.arch@bytedance.com Fixes: 3f913fc5f974 ("mm: fix missing handler for __GFP_NOWARN") Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Akinobu Mita <akinobu.mita@gmail.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Cc: Akinobu Mita <akinobu.mita@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Qi Zheng committed 3 years ago

Commit ea4452d1 parent de1ccfb4 files · +28 −11Browse files

Unified · Split

4 files

include/linux/fault-inject.h +5 −2
lib/fault-inject.c +8 −5
mm/failslab.c +10 −2
mm/page_alloc.c +5 −2

include/linux/fault-inject.h+5−2

@@ -20,7 +20,6 @@ struct fault_attr { · 19 unmodified lines
20	20	atomic_t space;
21	21	unsigned long verbose;
22	22	bool task_filter;
23		− bool no_warn;
24	23	unsigned long stacktrace_depth;
25	24	unsigned long require_start;
26	25	unsigned long require_end;
@@ -32,6 +31,10 @@ struct fault_attr { · 5 unmodified lines
32	31	struct dentry *dname;
33	32	};
34	33
	34	+enum fault_flags {
	35	+ FAULT_NOWARN = 1 << 0,
	36	+};
	37	+
35	38	#define FAULT_ATTR_INITIALIZER { \
36	39	.interval = 1, \
37	40	.times = ATOMIC_INIT(1), \
@@ -40,11 +43,11 @@ struct fault_attr { · 2 unmodified lines
40	43	.ratelimit_state = RATELIMIT_STATE_INIT_DISABLED, \
41	44	.verbose = 2, \
42	45	.dname = NULL, \
43		− .no_warn = false, \
44	46	}
45	47
46	48	#define DECLARE_FAULT_ATTR(name) struct fault_attr name = FAULT_ATTR_INITIALIZER
47	49	int setup_fault_attr(struct fault_attr attr, char str);
	50	+bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags);
48	51	bool should_fail(struct fault_attr *attr, ssize_t size);
49	52
50	53	#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS

lib/fault-inject.c+8−5

@@ -41,9 +41,6 @@ EXPORT_SYMBOL_GPL(setup_fault_attr); · 40 unmodified lines
41	41
42	42	static void fail_dump(struct fault_attr *attr)
43	43	{
44		− if (attr->no_warn)
45		− return;
46		−
47	44	if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
48	45	printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
49	46	"name %pd, interval %lu, probability %lu, "
@@ -103,7 +100,7 @@ static inline bool fail_stacktrace(struct fault_attr *attr) · 53 unmodified lines
103	100	* http://www.nongnu.org/failmalloc/
104	101	*/
105	102
106		−bool should_fail(struct fault_attr *attr, ssize_t size)
	103	+bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags)
107	104	{
108	105	if (in_task()) {
109	106	unsigned int fail_nth = READ_ONCE(current->fail_nth);
@@ -146,13 +143,19 @@ bool should_fail(struct fault_attr *attr, ssize_t size) · 36 unmodified lines
146	143	return false;
147	144
148	145	fail:
149		− fail_dump(attr);
	146	+ if (!(flags & FAULT_NOWARN))
	147	+ fail_dump(attr);
150	148
151	149	if (atomic_read(&attr->times) != -1)
152	150	atomic_dec_not_zero(&attr->times);
153	151
154	152	return true;
155	153	}
	154	+
	155	+bool should_fail(struct fault_attr *attr, ssize_t size)
	156	+{
	157	+ return should_fail_ex(attr, size, 0);
	158	+}
156	159	EXPORT_SYMBOL_GPL(should_fail);
157	160
158	161	#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS

mm/failslab.c+10−2

@@ -16,6 +16,8 @@ static struct { · 15 unmodified lines
16	16
17	17	bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags)
18	18	{
	19	+ int flags = 0;
	20	+
19	21	/* No fault-injection for bootstrap cache */
20	22	if (unlikely(s == kmem_cache))
21	23	return false;
@@ -30,10 +32,16 @@ bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags) · 8 unmodified lines
30	32	if (failslab.cache_filter && !(s->flags & SLAB_FAILSLAB))
31	33	return false;
32	34
	35	+ /*
	36	+ * In some cases, it expects to specify __GFP_NOWARN
	37	+ * to avoid printing any information(not just a warning),
	38	+ * thus avoiding deadlocks. See commit 6b9dbedbe349 for
	39	+ * details.
	40	+ */
33	41	if (gfpflags & __GFP_NOWARN)
34		− failslab.attr.no_warn = true;
	42	+ flags \|= FAULT_NOWARN;
35	43
36		− return should_fail(&failslab.attr, s->object_size);
	44	+ return should_fail_ex(&failslab.attr, s->object_size, flags);
37	45	}
38	46
39	47	static int __init setup_failslab(char *str)

mm/page_alloc.c+5−2

@@ -3887,6 +3887,8 @@ __setup("fail_page_alloc=", setup_fail_page_alloc); · 3886 unmodified lines
3887	3887
3888	3888	static bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
3889	3889	{
	3890	+ int flags = 0;
	3891	+
3890	3892	if (order < fail_page_alloc.min_order)
3891	3893	return false;
3892	3894	if (gfp_mask & __GFP_NOFAIL)
@@ -3897,10 +3899,11 @@ static bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order) · 4 unmodified lines
3897	3899	(gfp_mask & __GFP_DIRECT_RECLAIM))
3898	3900	return false;
3899	3901
	3902	+ /* See comment in __should_failslab() */
3900	3903	if (gfp_mask & __GFP_NOWARN)
3901		− fail_page_alloc.attr.no_warn = true;
	3904	+ flags \|= FAULT_NOWARN;
3902	3905
3903		− return should_fail(&fail_page_alloc.attr, 1 << order);
	3906	+ return should_fail_ex(&fail_page_alloc.attr, 1 << order, flags);
3904	3907	}
3905	3908
3906	3909	#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS

mm: fix unexpected changes to {failslab|fail_page_alloc}.attr

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