Re: WARNING in try_grab_page

[Yikebaer Aizezi <yikebaer61@gmail.com>]

I just tried this patch, it worked and the bug was not triggered.

David Howells <dhowells@redhat.com> 于2023年8月4日周五 21:35写道：
>
> Matthew Wilcox <willy@infradead.org> wrote:
>
> > On Fri, Aug 04, 2023 at 11:14:45AM +0800, Yikebaer Aizezi wrote:
> > > Just patched it, then I rerun the reproduce program, and I got this
> > > output from console:
> > >
> > > BUG: Bad page state in process POC  pfn:0eb8d
> > > page:ffffea00003ae340 refcount:0 mapcount:0 mapping:0000000000000000
> > > index:0x0 pfn:0xeb8d
> > > flags: 0xfff00000001000(reserved|node=0|zone=1|lastcpupid=0x7ff)
> > > page_type: 0xffffffff()
> > > raw: 00fff00000001000 ffffea00003ae348 ffffea00003ae348 0000000000000000
> > > raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
> > > page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
> > > page_owner info is not present (never set?)
> > > Modules linked in:
> > > CPU: 0 PID: 7959 Comm: POC Not tainted 6.5.0-rc2 #2
> > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> > > rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> > > Call Trace:
> > >  <TASK>
> > >  __dump_stack lib/dump_stack.c:88 [inline]
> > >  dump_stack_lvl+0xd4/0xf0 lib/dump_stack.c:106
> > >  bad_page+0x71/0x1a0 mm/page_alloc.c:533
> > >  free_page_is_bad_report mm/page_alloc.c:974 [inline]
> > >  free_page_is_bad mm/page_alloc.c:984 [inline]
> > >  free_pages_prepare mm/page_alloc.c:1153 [inline]
> > >  free_unref_page_prepare+0x5f3/0xb50 mm/page_alloc.c:2348
> > >  free_unref_page+0x2f/0x3c0 mm/page_alloc.c:2443
> > >  __folio_put_small mm/swap.c:106 [inline]
> > >  __folio_put+0xa2/0x110 mm/swap.c:129
> > >  folio_put include/linux/mm.h:1423 [inline]
> > >  put_page include/linux/mm.h:1492 [inline]
> > >  extract_user_to_sg lib/scatterlist.c:1151 [inline]
> >
> > Ohh.  I think this is something Dave Howells has a patch for.
> >
> > >  extract_iter_to_sg lib/scatterlist.c:1349 [inline]
> > >  extract_iter_to_sg+0x11ec/0x1570 lib/scatterlist.c:1339
> > >  hash_sendmsg+0x487/0xf50 crypto/algif_hash.c:119
> > >  sock_sendmsg_nosec net/socket.c:725 [inline]
> > >  sock_sendmsg+0xcf/0x170 net/socket.c:748
> > >  ____sys_sendmsg+0x676/0x860 net/socket.c:2494
> > >  ___sys_sendmsg+0x109/0x1a0 net/socket.c:2548
> > >  __sys_sendmsg+0xe4/0x1b0 net/socket.c:2577
> > >  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> > >  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> > >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> This might be the fix you're looking for.
>
> https://lore.kernel.org/linux-crypto/20571.1690369076@warthog.procyon.org.uk/
>
> Andrew has it in mm-hotfixes-unstable.
>
> David
>