Find a file
Gang He 2d797e9ff9 ocfs2: fix oops when writing cloned file
Writing a cloned file triggers a kernel oops and the user-space command
process is also killed by the system.  The bug can be reproduced stably
via:

1) create a file under ocfs2 file system directory.

  journalctl -b > aa.txt

2) create a cloned file for this file.

  reflink aa.txt bb.txt

3) write the cloned file with dd command.

  dd if=/dev/zero of=bb.txt bs=512 count=1 conv=notrunc

The dd command is killed by the kernel, then you can see the oops message
via dmesg command.

[  463.875404] BUG: kernel NULL pointer dereference, address: 0000000000000028
[  463.875413] #PF: supervisor read access in kernel mode
[  463.875416] #PF: error_code(0x0000) - not-present page
[  463.875418] PGD 0 P4D 0
[  463.875425] Oops: 0000 [#1] SMP PTI
[  463.875431] CPU: 1 PID: 2291 Comm: dd Tainted: G           OE     5.3.16-2-default
[  463.875433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
[  463.875500] RIP: 0010:ocfs2_refcount_cow+0xa4/0x5d0 [ocfs2]
[  463.875505] Code: 06 89 6c 24 38 89 eb f6 44 24 3c 02 74 be 49 8b 47 28
[  463.875508] RSP: 0018:ffffa2cb409dfce8 EFLAGS: 00010202
[  463.875512] RAX: ffff8b1ebdca8000 RBX: 0000000000000001 RCX: ffff8b1eb73a9df0
[  463.875515] RDX: 0000000000056a01 RSI: 0000000000000000 RDI: 0000000000000000
[  463.875517] RBP: 0000000000000001 R08: ffff8b1eb73a9de0 R09: 0000000000000000
[  463.875520] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
[  463.875522] R13: ffff8b1eb922f048 R14: 0000000000000000 R15: ffff8b1eb922f048
[  463.875526] FS:  00007f8f44d15540(0000) GS:ffff8b1ebeb00000(0000) knlGS:0000000000000000
[  463.875529] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  463.875532] CR2: 0000000000000028 CR3: 000000003c17a000 CR4: 00000000000006e0
[  463.875546] Call Trace:
[  463.875596]  ? ocfs2_inode_lock_full_nested+0x18b/0x960 [ocfs2]
[  463.875648]  ocfs2_file_write_iter+0xaf8/0xc70 [ocfs2]
[  463.875672]  new_sync_write+0x12d/0x1d0
[  463.875688]  vfs_write+0xad/0x1a0
[  463.875697]  ksys_write+0xa1/0xe0
[  463.875710]  do_syscall_64+0x60/0x1f0
[  463.875743]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  463.875758] RIP: 0033:0x7f8f4482ed44
[  463.875762] Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 80 00 00 00
[  463.875765] RSP: 002b:00007fff300a79d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[  463.875769] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f8f4482ed44
[  463.875771] RDX: 0000000000000200 RSI: 000055f771b5c000 RDI: 0000000000000001
[  463.875774] RBP: 0000000000000200 R08: 00007f8f44af9c78 R09: 0000000000000003
[  463.875776] R10: 000000000000089f R11: 0000000000000246 R12: 000055f771b5c000
[  463.875779] R13: 0000000000000200 R14: 0000000000000000 R15: 000055f771b5c000

This regression problem was introduced by commit e74540b285 ("ocfs2:
protect extent tree in ocfs2_prepare_inode_for_write()").

Link: http://lkml.kernel.org/r/20200121050153.13290-1-ghe@suse.com
Fixes: e74540b285 ("ocfs2: protect extent tree in ocfs2_prepare_inode_for_write()").
Signed-off-by: Gang He <ghe@suse.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-02-04 03:05:23 +00:00
arch kgdb patches for 5.6-rc1 2020-02-03 16:59:51 +00:00
block SCSI misc on 20200129 2020-01-29 18:16:16 -08:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2020-01-28 15:38:56 -08:00
Documentation - New Drivers 2020-02-03 14:51:57 +00:00
drivers Char/Misc fix for 5.6-rc1 2020-02-03 14:57:33 +00:00
fs ocfs2: fix oops when writing cloned file 2020-02-04 03:05:23 +00:00
include kgdb patches for 5.6-rc1 2020-02-03 16:59:51 +00:00
init init/main.c: fix misleading "This architecture does not have kernel memory protection" message 2020-01-31 10:30:41 -08:00
ipc treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
kernel kgdb patches for 5.6-rc1 2020-02-03 16:59:51 +00:00
lib kcov: ignore fault-inject and stacktrace 2020-01-31 10:30:41 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm Merge branch 'akpm' (patches from Andrew) 2020-01-31 12:16:36 -08:00
net Merge branch 'akpm' (patches from Andrew) 2020-01-31 12:16:36 -08:00
samples drm pull for 5.6-rc1 2020-01-30 08:04:01 -08:00
scripts Kconfig updates for v5.6 2020-02-01 10:25:55 -08:00
security linux-kselftest-5.6-rc1-kunit 2020-01-29 15:25:34 -08:00
sound sound updates for 5.6-rc1 2020-01-28 16:26:57 -08:00
tools - Most of the commits here are work to enable host-initiated hibernation 2020-02-03 14:42:03 +00:00
usr initramfs: do not show compression mode choice if INITRAMFS_SOURCE is empty 2020-02-03 17:31:43 +00:00
virt Merge branch 'cve-2019-3016' into kvm-next-5.6 2020-01-30 18:47:59 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap pci-v5.6-changes 2020-01-31 14:48:54 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS open: introduce openat2(2) syscall 2020-01-18 09:19:18 -05:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS pci-v5.6-changes 2020-01-31 14:48:54 -08:00
Makefile Kbuild updates for v5.6 2020-02-01 10:01:52 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.