From: Hugh Dickins <hughd@google.com>
To: Matthew Wilcox <willy@infradead.org>, Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: amusing SLUB compaction bug when CC_OPTIMIZE_FOR_SIZE
Date: Tue, 27 Sep 2022 22:16:35 -0700 (PDT) [thread overview]
Message-ID: <ea96c78c-e1dc-1364-e91-51909f82388b@google.com> (raw)
It's a bug in linux-next, but taking me too long to identify which
commit is "to blame", so let me throw it over to you without more
delay: I think __PageMovable() now needs to check !PageSlab().
I had made a small experimental change somewhere, rebuilt and rebooted,
was not surprised to crash once swapping and compaction came in,
but was surprised to find the crash in isolate_movable_page(),
called by compaction's isolate_migratepages_block().
page->mapping was ffffffff811303aa, which qualifies as __PageMovable(),
which expects struct movable_operations at page->mapping minus low bits.
But ffffffff811303aa was the address of SLUB's rcu_free_slab(): I have
CONFIG_CC_OPTIMIZE_FOR_SIZE=y, so function addresses may have low bits set.
Over to you! Thanks,
Hugh
next reply other threads:[~2022-09-28 5:16 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-28 5:16 Hugh Dickins [this message]
2022-09-28 5:49 ` amusing SLUB compaction bug when CC_OPTIMIZE_FOR_SIZE Hyeonggon Yoo
2022-09-28 13:48 ` Joel Fernandes
2022-09-28 15:09 ` Hyeonggon Yoo
2022-09-28 16:20 ` Vlastimil Babka
2022-09-28 17:50 ` Hugh Dickins
2022-09-29 9:58 ` Vlastimil Babka
2022-09-29 21:54 ` Hugh Dickins
2022-09-30 7:39 ` Vlastimil Babka
2022-09-30 10:45 ` Hugh Dickins
2022-09-30 11:02 ` David Laight
2022-09-30 16:21 ` Hugh Dickins
2022-09-30 21:34 ` David Laight
2022-10-02 5:48 ` Hyeonggon Yoo
2022-10-03 17:00 ` Matthew Wilcox
2022-10-04 14:26 ` Hyeonggon Yoo
2022-10-04 14:40 ` Matthew Wilcox
2022-10-05 11:07 ` Hyeonggon Yoo
2022-10-24 14:35 ` Vlastimil Babka
2022-10-24 15:06 ` Matthew Wilcox
2022-10-24 15:24 ` Vlastimil Babka
2022-10-24 16:49 ` Vlastimil Babka
2022-10-25 4:19 ` Hugh Dickins
2022-10-25 9:17 ` Vlastimil Babka
2022-10-25 15:45 ` Hugh Dickins
2022-10-25 13:47 ` Hyeonggon Yoo
2022-10-25 14:08 ` Vlastimil Babka
2022-10-26 10:52 ` Vlastimil Babka
2022-10-26 12:29 ` Hyeonggon Yoo
2022-11-04 15:57 ` Vlastimil Babka
2022-09-29 11:53 ` David Laight
2022-09-29 13:01 ` Vlastimil Babka
2022-09-29 14:04 ` David Laight
2022-09-28 17:56 ` Hyeonggon Yoo
2022-09-28 19:53 ` Joel Fernandes
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