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| author | Vlastimil Babka <vbabka@suse.cz> | 2016-12-13 01:44:35 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-13 03:55:08 +0100 |
| commit | 46e8a3a08c23d07d0f21fabeed182b671af68c93 (patch) | |
| tree | e7a7e0f1aec3c90a1cf0fbcc959b0f6c79c0a130 /mm/debug.c | |
| parent | mm: THP page cache support for ppc64 (diff) | |
| download | linux-46e8a3a08c23d07d0f21fabeed182b671af68c93.tar.xz linux-46e8a3a08c23d07d0f21fabeed182b671af68c93.zip | |
mm, debug: print raw struct page data in __dump_page()
__dump_page() is used when a page metadata inconsistency is detected,
either by standard runtime checks, or extra checks in CONFIG_DEBUG_VM
builds. It prints some of the relevant metadata, but not the whole
struct page, which is based on unions and interpretation is dependent on
the context.
This means that sometimes e.g. a VM_BUG_ON_PAGE() checks certain field,
which is however not printed by __dump_page() and the resulting bug
report may then lack clues that could help in determining the root
cause. This patch solves the problem by simply printing the whole
struct page word by word, so no part is missing, but the interpretation
of the data is left to developers. This is similar to e.g. x86_64 raw
stack dumps.
Example output:
page:ffffea00000475c0 count:1 mapcount:0 mapping: (null) index:0x0
flags: 0x100000000000400(reserved)
raw: 0100000000000400 0000000000000000 0000000000000000 00000001ffffffff
raw: ffffea00000475e0 ffffea00000475e0 0000000000000000 0000000000000000
page dumped because: VM_BUG_ON_PAGE(1)
[aryabinin@virtuozzo.com: suggested print_hex_dump()]
Link: http://lkml.kernel.org/r/2ff83214-70fe-741e-bf05-fe4a4073ec3e@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/debug.c')
| -rw-r--r-- | mm/debug.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/mm/debug.c b/mm/debug.c index 9feb699c5d25..db1cd26d8752 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -59,6 +59,10 @@ void __dump_page(struct page *page, const char *reason) pr_emerg("flags: %#lx(%pGp)\n", page->flags, &page->flags); + print_hex_dump(KERN_ALERT, "raw: ", DUMP_PREFIX_NONE, 32, + sizeof(unsigned long), page, + sizeof(struct page), false); + if (reason) pr_alert("page dumped because: %s\n", reason); |