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From: Hyesoo Yu <hyesoo.yu@samsung.com>
Cc: janghyuck.kim@samsung.com, Hyesoo Yu <hyesoo.yu@samsung.com>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Hyeonggon Yoo <42.hyeyoo@gmail.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [PATCH] mm: slub: Print the broken data before restoring slub.
Date: Mon, 20 Jan 2025 17:30:21 +0900	[thread overview]
Message-ID: <20250120083023.4162932-1-hyesoo.yu@samsung.com> (raw)
In-Reply-To: <CGME20250120083144epcas2p369584af764b617c3d2cb2a0568a45d6c@epcas2p3.samsung.com>

Previously, the restore occured after printing the object in slub.
After commit 47d911b ("slab: make check_object() more consistent"),
the bytes are printed after the restore. This information about the bytes
before the restore is highly valuable for debugging purpose.
For instance, in a event of cache issue, it displays byte patterns
by breaking them down into 64-bytes units. Without this information,
we can only speculate on how it was broken. Hence the corrupted regions
are printed prior to the restoration process.

Signed-off-by: Hyesoo Yu <hyesoo.yu@samsung.com>
Change-Id: Iac1df0526808edc2318f9988c757cdc3e40ae4b2
---
 mm/slub.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/slub.c b/mm/slub.c
index c2151c9fee22..48cefc969480 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1207,6 +1207,7 @@ check_bytes_and_report(struct kmem_cache *s, struct slab *slab,
 					fault[0], value);
 
 skip_bug_print:
+	print_section(KERN_ERR, "Corrupt  ", fault, end - fault);
 	restore_bytes(s, what, value, fault, end);
 	return 0;
 }
-- 
2.48.0



       reply	other threads:[~2025-01-20  8:31 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20250120083144epcas2p369584af764b617c3d2cb2a0568a45d6c@epcas2p3.samsung.com>
2025-01-20  8:30 ` Hyesoo Yu [this message]
2025-01-21 13:35   ` Hyeonggon Yoo
2025-01-22  3:25     ` Chengming Zhou
2025-01-22  5:42       ` Hyesoo Yu
2025-01-22  5:27     ` Hyesoo Yu

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