]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
mm, page_owner: decouple freeing stack trace from debug_pagealloc
authorVlastimil Babka <vbabka@suse.cz>
Mon, 14 Oct 2019 21:11:44 +0000 (14:11 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Mon, 14 Oct 2019 22:04:00 +0000 (15:04 -0700)
commit0fe9a448a029a11d7211fcc2ebe9023d7fd31792
treea516a11ebf5dda36d09ae695b126720d35d9626c
parent5556cfe8d994d5e7b4d50fd91597b8dc0b3a82fd
mm, page_owner: decouple freeing stack trace from debug_pagealloc

Commit 8974558f49a6 ("mm, page_owner, debug_pagealloc: save and dump
freeing stack trace") enhanced page_owner to also store freeing stack
trace, when debug_pagealloc is also enabled.  KASAN would also like to
do this [1] to improve error reports to debug e.g. UAF issues.

Kirill has suggested that the freeing stack trace saving should be also
possible to be enabled separately from KASAN or debug_pagealloc, i.e.
with an extra boot option.  Qian argued that we have enough options
already, and avoiding the extra overhead is not worth the complications
in the case of a debugging option.  Kirill noted that the extra stack
handle in struct page_owner requires 0.1% of memory.

This patch therefore enables free stack saving whenever page_owner is
enabled, regardless of whether debug_pagealloc or KASAN is also enabled.
KASAN kernels booted with page_owner=on will thus benefit from the
improved error reports.

[1] https://bugzilla.kernel.org/show_bug.cgi?id=203967

[vbabka@suse.cz: v3]
Link: http://lkml.kernel.org/r/20191007091808.7096-3-vbabka@suse.cz
Link: http://lkml.kernel.org/r/20190930122916.14969-3-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Qian Cai <cai@lca.pw>
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Suggested-by: Walter Wu <walter-zh.wu@mediatek.com>
Suggested-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Suggested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Suggested-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Documentation/dev-tools/kasan.rst
mm/page_owner.c