Revision eecc1e426d681351a6026a7d3e7d225f38955b6c authored by Hugh Dickins on 12 January 2014, 09:25:21 UTC, committed by Linus Torvalds on 12 January 2014, 09:47:15 UTC
We see General Protection Fault on RSI in copy_page_rep: that RSI is
what you get from a NULL struct page pointer.
RIP: 0010:[<ffffffff81154955>] [<ffffffff81154955>] copy_page_rep+0x5/0x10
RSP: 0000:ffff880136e15c00 EFLAGS: 00010286
RAX: ffff880000000000 RBX: ffff880136e14000 RCX: 0000000000000200
RDX: 6db6db6db6db6db7 RSI: db73880000000000 RDI: ffff880dd0c00000
RBP: ffff880136e15c18 R08: 0000000000000200 R09: 000000000005987c
R10: 000000000005987c R11: 0000000000000200 R12: 0000000000000001
R13: ffffea00305aa000 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f195752f700(0000) GS:ffff880c7fc20000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000093010000 CR3: 00000001458e1000 CR4: 00000000000027e0
Call Trace:
copy_user_huge_page+0x93/0xab
do_huge_pmd_wp_page+0x710/0x815
handle_mm_fault+0x15d8/0x1d70
__do_page_fault+0x14d/0x840
do_page_fault+0x2f/0x90
page_fault+0x22/0x30
do_huge_pmd_wp_page() tests is_huge_zero_pmd(orig_pmd) four times: but
since shrink_huge_zero_page() can free the huge_zero_page, and we have
no hold of our own on it here (except where the fourth test holds
page_table_lock and has checked pmd_same), it's possible for it to
answer yes the first time, but no to the second or third test. Change
all those last three to tests for NULL page.
(Note: this is not the same issue as trinity's DEBUG_PAGEALLOC BUG
in copy_page_rep with RSI: ffff88009c422000, reported by Sasha Levin
in https://lkml.org/lkml/2013/3/29/103. I believe that one is due
to the source page being split, and a tail page freed, while copy
is in progress; and not a problem without DEBUG_PAGEALLOC, since
the pmd_same check will prevent a miscopy from being made visible.)
Fixes: 97ae17497e99 ("thp: implement refcounting for huge zero page")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: stable@vger.kernel.org # v3.10 v3.11 v3.12
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 518d00b
kc.h
/*
* PPS kernel consumer API header
*
* Copyright (C) 2009-2010 Alexander Gordeev <lasaine@lvk.cs.msu.su>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef LINUX_PPS_KC_H
#define LINUX_PPS_KC_H
#include <linux/errno.h>
#include <linux/pps_kernel.h>
#ifdef CONFIG_NTP_PPS
extern int pps_kc_bind(struct pps_device *pps,
struct pps_bind_args *bind_args);
extern void pps_kc_remove(struct pps_device *pps);
extern void pps_kc_event(struct pps_device *pps,
struct pps_event_time *ts, int event);
#else /* CONFIG_NTP_PPS */
static inline int pps_kc_bind(struct pps_device *pps,
struct pps_bind_args *bind_args) { return -EOPNOTSUPP; }
static inline void pps_kc_remove(struct pps_device *pps) {}
static inline void pps_kc_event(struct pps_device *pps,
struct pps_event_time *ts, int event) {}
#endif /* CONFIG_NTP_PPS */
#endif /* LINUX_PPS_KC_H */
Computing file changes ...
