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From: Jan Kara <jack@suse.cz>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux MM <linux-mm@kvack.org>, Jan Kara <jack@suse.cz>,
	stable <stable@vger.kernel.org>,
	linux-nvdimm <linux-nvdimm@lists.01.org>
Subject: Re: [PATCH] mm: Preserve _PAGE_DEVMAP across mprotect() calls
Date: Wed, 10 Oct 2018 09:45:23 +0200	[thread overview]
Message-ID: <20181010074523.GA11507@quack2.suse.cz> (raw)
In-Reply-To: <CAPcyv4jExSvW8xSe_LYAYvjgBd=gfKdvrqtojybK0wfu9GFNLA@mail.gmail.com>

On Tue 09-10-18 10:55:14, Dan Williams wrote:
> On Tue, Oct 9, 2018 at 3:19 AM Jan Kara <jack@suse.cz> wrote:
> >
> > Currently _PAGE_DEVMAP bit is not preserved in mprotect(2) calls. As a
> > result we will see warnings such as:
> >
> > BUG: Bad page map in process JobWrk0013  pte:800001803875ea25 pmd:7624381067
> > addr:00007f0930720000 vm_flags:280000f9 anon_vma:          (null) mapping:ffff97f2384056f0 index:0
> > file:457-000000fe00000030-00000009-000000ca-00000001_2001.fileblock fault:xfs_filemap_fault [xfs] mmap:xfs_file_mmap [xfs] readpage:          (null)
> > CPU: 3 PID: 15848 Comm: JobWrk0013 Tainted: G        W          4.12.14-2.g7573215-default #1 SLE12-SP4 (unreleased)
> > Hardware name: Intel Corporation S2600WFD/S2600WFD, BIOS SE5C620.86B.01.00.0833.051120182255 05/11/2018
> > Call Trace:
> >  dump_stack+0x5a/0x75
> >  print_bad_pte+0x217/0x2c0
> >  ? enqueue_task_fair+0x76/0x9f0
> >  _vm_normal_page+0xe5/0x100
> >  zap_pte_range+0x148/0x740
> >  unmap_page_range+0x39a/0x4b0
> >  unmap_vmas+0x42/0x90
> >  unmap_region+0x99/0xf0
> >  ? vma_gap_callbacks_rotate+0x1a/0x20
> >  do_munmap+0x255/0x3a0
> >  vm_munmap+0x54/0x80
> >  SyS_munmap+0x1d/0x30
> >  do_syscall_64+0x74/0x150
> >  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
> > ...
> >
> > when mprotect(2) gets used on DAX mappings. Also there is a wide variety
> > of other failures that can result from the missing _PAGE_DEVMAP flag
> > when the area gets used by get_user_pages() later.
> >
> > Fix the problem by including _PAGE_DEVMAP in a set of flags that get
> > preserved by mprotect(2).
> >
> > Fixes: 69660fd797c3 ("x86, mm: introduce _PAGE_DEVMAP")
> > Fixes: ebd31197931d ("powerpc/mm: Add devmap support for ppc64")
> > CC: stable@vger.kernel.org
> > Signed-off-by: Jan Kara <jack@suse.cz>
> 
> Looks good, do you want me to take this upstream along with the livelock fix?

Yes, I think that would be best. Thanks!

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR
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  reply	other threads:[~2018-10-10  7:45 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-09 10:19 Jan Kara
2018-10-09 13:07 ` Michal Hocko
2018-10-09 17:55 ` Dan Williams
2018-10-10  7:45   ` Jan Kara [this message]
2018-10-09 18:38 ` Johannes Thumshirn

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