Re: [Question] race condition in mm/page_alloc.c regarding page->lru?

From: TAO HU
Date: Fri Apr 02 2010 - 03:01:06 EST

Hi, kamezawa hiroyu

Thanks for the hint!

Hi, Minchan Kim

Sorry. Not exactly sure your idea about <grep "page handling">.
Below is a result of $ grep -n -r "list_del(&page->lru)" * in our src tree

arch/s390/mm/pgtable.c:83: list_del(&page->lru);
arch/s390/mm/pgtable.c:226: list_del(&page->lru);
arch/x86/mm/pgtable.c:60: list_del(&page->lru);
drivers/xen/balloon.c:154: list_del(&page->lru);
drivers/virtio/virtio_balloon.c:143: list_del(&page->lru);
fs/cifs/file.c:1780: list_del(&page->lru);
fs/btrfs/extent_io.c:2584: list_del(&page->lru);
fs/mpage.c:388: list_del(&page->lru);
include/linux/mm_inline.h:37: list_del(&page->lru);
include/linux/mm_inline.h:47: list_del(&page->lru);
kernel/kexec.c:391: list_del(&page->lru);
kernel/kexec.c:711: list_del(&page->lru);
mm/migrate.c:69: list_del(&page->lru);
mm/migrate.c:695: list_del(&page->lru);
mm/hugetlb.c:467: list_del(&page->lru);
mm/hugetlb.c:509: list_del(&page->lru);
mm/hugetlb.c:836: list_del(&page->lru);
mm/hugetlb.c:844: list_del(&page->lru);
mm/hugetlb.c:900: list_del(&page->lru);
mm/hugetlb.c:1130: list_del(&page->lru);
mm/hugetlb.c:1809: list_del(&page->lru);
mm/vmscan.c:597: list_del(&page->lru);
mm/vmscan.c:1148: list_del(&page->lru);
mm/vmscan.c:1246: list_del(&page->lru);
mm/slub.c:827: list_del(&page->lru);
mm/slub.c:1249: list_del(&page->lru);
mm/slub.c:1263: list_del(&page->lru);
mm/slub.c:2419: list_del(&page->lru);
mm/slub.c:2809: list_del(&page->lru);
mm/readahead.c:65: list_del(&page->lru);
mm/readahead.c:100: list_del(&page->lru);
mm/page_alloc.c:532: list_del(&page->lru);
mm/page_alloc.c:679: list_del(&page->lru);
mm/page_alloc.c:741: list_del(&page->lru);
mm/page_alloc.c:820: list_del(&page->lru);
mm/page_alloc.c:1107: list_del(&page->lru);
mm/page_alloc.c:4784: list_del(&page->lru);

On Fri, Apr 2, 2010 at 1:15 PM, Minchan Kim <> wrote:
> On Fri, Apr 2, 2010 at 2:04 PM, KAMEZAWA Hiroyuki
> <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
>> On Fri, 2 Apr 2010 11:51:33 +0800
>> TAO HU <tghk48@xxxxxxxxxxxx> wrote:
>>> 2 patches related to page_alloc.c were applied.
>>> Does anyone see a connection between the 2 patches and the panic?
>>> NOTE: the full patches are attached.
>> I don't think there are relationship between patches and your panic.
>> BTW, there is other case about the backlog rather than race in alloc_pages()
>> itself. If someone list_del(&page->lru) and the page is already freed,
>> you'll see the same backlog later.
>> Then, I doubt use-after-free case rather than complicated races.
> It does make sense.
> Please, grep "page handling" by out-of-mainline code.
> If you found out, Please, post it.
> --
> Kind regards,
> Minchan Kim
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