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From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Hugh Dickins <hughd@google.com>,
	Jerome Marchand <jmarchan@redhat.com>,
	linux-kernel@vger.kernel.org,
	Naoya Horiguchi <nao.horiguchi@gmail.com>
Subject: Re: [PATCH v4 13/13] mincore: apply page table walker on do_mincore()
Date: Wed, 9 Jul 2014 16:34:36 +0300	[thread overview]
Message-ID: <20140709133436.GA18391@node.dhcp.inet.fi> (raw)
In-Reply-To: <1404234451-21695-14-git-send-email-n-horiguchi@ah.jp.nec.com>

On Tue, Jul 01, 2014 at 01:07:31PM -0400, Naoya Horiguchi wrote:
> This patch makes do_mincore() use walk_page_vma(), which reduces many lines
> of code by using common page table walk code.
> 
> ChangeLog v4:
> - remove redundant vma
> 
> ChangeLog v3:
> - add NULL vma check in mincore_unmapped_range()
> - don't use pte_entry()
> 
> ChangeLog v2:
> - change type of args of callbacks to void *
> - move definition of mincore_walk to the start of the function to fix compiler
>   warning
> 
> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

Trinity crases this implementation of mincore pretty easily:

[   42.775369] BUG: unable to handle kernel paging request at ffff88007bb61000
[   42.776656] IP: [<ffffffff81126f8f>] mincore_unmapped_range+0xdf/0x100
[   42.777560] PGD 2ef6067 PUD 87fa01067 PMD 87f823067 PTE 800000007bb61060
[   42.778529] Oops: 0002 [#1] SMP DEBUG_PAGEALLOC
[   42.779106] Modules linked in:
[   42.779106] CPU: 0 PID: 917 Comm: trinity-c27 Not tainted 3.16.0-rc4-next-20140709-00013-g28e4629f71a8 #1450
[   42.779106] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   42.779106] task: ffff880852e98110 ti: ffff880844024000 task.ti: ffff880844024000
[   42.779106] RIP: 0010:[<ffffffff81126f8f>]  [<ffffffff81126f8f>] mincore_unmapped_range+0xdf/0x100
[   42.779106] RSP: 0018:ffff880844027df0  EFLAGS: 00010202
[   42.779106] RAX: 000000000000001c RBX: 00007fc300000000 RCX: 00003ffffffff000
[   42.779106] RDX: 000000000000001b RSI: ffff88007bb60fe5 RDI: 00007fc2c2c00000
[   42.779106] RBP: ffff880844027e28 R08: 00007fc2c2e00000 R09: 0000000000000000
[   42.779106] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000200
[   42.779106] R13: ffff88007bb60fe5 R14: ffff880855a80018 R15: 00007fc2c2c00000
[   42.779106] FS:  00007fc345666700(0000) GS:ffff880859600000(0000) knlGS:0000000000000000
[   42.779106] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   42.779106] CR2: ffff88007bb61000 CR3: 0000000852dfd000 CR4: 00000000000006f0
[   42.779106] Stack:
[   42.779106]  ffff880844027f10 ffff88007bb60fe5 00007fc300000000 00007fc2c2e00000
[   42.779106]  00007fc2c1e1b000 ffff880844027f10 00007fc2c2c00000 ffff880844027eb8
[   42.779106]  ffffffff81135bfe 00007fc341c1bfff ffff880000000000 ffff880852dfd7f8
[   42.779106] Call Trace:
[   42.779106]  [<ffffffff81135bfe>] __walk_page_range+0x1ae/0x450
[   42.779106]  [<ffffffff81136051>] walk_page_vma+0x71/0x90
[   42.779106]  [<ffffffff8112741e>] SyS_mincore+0x1de/0x270
[   42.779106]  [<ffffffff810949fd>] ? trace_hardirqs_on+0xd/0x10
[   42.779106]  [<ffffffff81126fb0>] ? mincore_unmapped_range+0x100/0x100
[   42.779106]  [<ffffffff81126eb0>] ? mincore_page+0xa0/0xa0
[   42.779106]  [<ffffffff81126dc0>] ? handle_mm_fault+0xd30/0xd30
[   42.779106]  [<ffffffff81746b52>] system_call_fastpath+0x16/0x1b
[   42.779106] Code: 83 c4 10 31 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 40 00 31 d2 31 c0 4d 85 e4 4c 8b 6d d0 74 d3 0f 1f 00 48 8b 75 d0 83 c0 01 <c6> 04 16 00 48 63 d0 49 39 d4 77 ed eb b3 48 89 fe 4c 89 f7 e8 
[   42.779106] RIP  [<ffffffff81126f8f>] mincore_unmapped_range+0xdf/0x100
[   42.779106]  RSP <ffff880844027df0>
[   42.779106] CR2: ffff88007bb61000
[   42.779106] ---[ end trace 3fac62521b6b0cb0 ]---
[   42.779106] Kernel panic - not syncing: Fatal exception
[   42.779106] Kernel Offset: 0x0 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffff9fffffff)


Looks like 'vec' overflow. I don't see what could prevent do_mincore() to
write more than PAGE_SIZE to 'vec'.

-- 
 Kirill A. Shutemov

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  reply	other threads:[~2014-07-09 13:34 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-01 17:07 [PATCH v4 00/13] pagewalk: improve vma handling, apply to new users Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 01/13] mm/pagewalk: remove pgd_entry() and pud_entry() Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 02/13] pagewalk: improve vma handling Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 03/13] pagewalk: add walk_page_vma() Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 04/13] smaps: remove mem_size_stats->vma and use walk_page_vma() Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 05/13] clear_refs: remove clear_refs_private->vma and introduce clear_refs_test_walk() Naoya Horiguchi
2014-07-10 11:32   ` Kirill A. Shutemov
2014-07-10 13:27     ` Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 06/13] pagemap: use walk->vma instead of calling find_vma() Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 07/13] numa_maps: fix typo in gather_hugetbl_stats Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 08/13] numa_maps: remove numa_maps->vma Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 09/13] memcg: cleanup preparation for page table walk Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 10/13] arch/powerpc/mm/subpage-prot.c: use walk->vma and walk_page_vma() Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 11/13] mempolicy: apply page table walker on queue_pages_range() Naoya Horiguchi
2014-07-01 21:00   ` Dave Hansen
2014-07-01 21:51     ` Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 12/13] mm: /proc/pid/clear_refs: avoid split_huge_page() Naoya Horiguchi
2014-07-01 17:07 ` [PATCH v4 13/13] mincore: apply page table walker on do_mincore() Naoya Horiguchi
2014-07-09 13:34   ` Kirill A. Shutemov [this message]
2014-07-09 21:36     ` Naoya Horiguchi
2014-07-10 10:06       ` Kirill A. Shutemov
2014-07-10 16:35         ` Naoya Horiguchi

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