This is a note to let you know that I've just added the patch titled
thp, mm: fix crash due race in MADV_FREE handling
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
thp-mm-fix-crash-due-race-in-madv_free-handling.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From bbf29ffc7f963bb894f84f0580c70cfea01c3892 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Date: Thu, 6 Jul 2017 15:35:28 -0700
Subject: thp, mm: fix crash due race in MADV_FREE handling
From: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
commit bbf29ffc7f963bb894f84f0580c70cfea01c3892 upstream.
Reinette reported the following crash:
BUG: Bad page state in process log2exe pfn:57600
page:ffffea00015d8000 count:0 mapcount:0 mapping: (null) index:0x20200
flags: 0x4000000000040019(locked|uptodate|dirty|swapbacked)
raw: 4000000000040019 0000000000000000 0000000000020200 00000000ffffffff
raw: ffffea00015d8020 ffffea00015d8020 0000000000000000 0000000000000000
page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
bad because of flags: 0x1(locked)
Modules linked in: rfcomm 8021q bnep intel_rapl x86_pkg_temp_thermal coretemp efivars btusb btrtl btbcm pwm_lpss_pci snd_hda_codec_hdmi btintel pwm_lpss snd_hda_codec_realtek snd_soc_skl snd_hda_codec_generic snd_soc_skl_ipc spi_pxa2xx_platform snd_soc_sst_ipc snd_soc_sst_dsp i2c_designware_platform i2c_designware_core snd_hda_ext_core snd_soc_sst_match snd_hda_intel snd_hda_codec mei_me snd_hda_core mei snd_soc_rt286 snd_soc_rl6347a snd_soc_core efivarfs
CPU: 1 PID: 354 Comm: log2exe Not tainted 4.12.0-rc7-test-test #19
Hardware name: Intel corporation NUC6CAYS/NUC6CAYB, BIOS AYAPLCEL.86A.0027.2016.1108.1529 11/08/2016
Call Trace:
bad_page+0x16a/0x1f0
free_pages_check_bad+0x117/0x190
free_hot_cold_page+0x7b1/0xad0
__put_page+0x70/0xa0
madvise_free_huge_pmd+0x627/0x7b0
madvise_free_pte_range+0x6f8/0x1150
__walk_page_range+0x6b5/0xe30
walk_page_range+0x13b/0x310
madvise_free_page_range.isra.16+0xad/0xd0
madvise_free_single_vma+0x2e4/0x470
SyS_madvise+0x8ce/0x1450
If somebody frees the page under us and we hold the last reference to
it, put_page() would attempt to free the page before unlocking it.
The fix is trivial reorder of operations.
Dave said:
"I came up with the exact same patch. For posterity, here's the test
case, generated by syzkaller and trimmed down by Reinette:
https://www.sr71.net/~dave/intel/log2.c
And the config that helps detect this:
https://www.sr71.net/~dave/intel/config-log2";
Fixes: b8d3c4c3009d ("mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called")
Link: http://lkml.kernel.org/r/20170628101249.17879-1-kirill.shutemov@xxxxxxxxxxxxxxx
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reported-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1373,8 +1373,8 @@ bool madvise_free_huge_pmd(struct mmu_ga
get_page(page);
spin_unlock(ptl);
split_huge_page(page);
- put_page(page);
unlock_page(page);
+ put_page(page);
goto out_unlocked;
}
Patches currently in stable-queue which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
queue-4.9/thp-mm-fix-crash-due-race-in-madv_free-handling.patch