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Filename Latest commit message Latest commit date
Alex Wu ee37d7314a md/raid10: Fix raid10 replace hang when new added disk faulty
[Symptom]

Resync thread hang when new added disk faulty during replacing.

[Root Cause]

In raid10_sync_request(), we expect to issue a bio with callback
end_sync_read(), and a bio with callback end_sync_write().

In normal situation, we will add resyncing sectors into
mddev->recovery_active when raid10_sync_request() returned, and sub
resynced sectors from mddev->recovery_active when end_sync_write()
calls end_sync_request().

If new added disk, which are replacing the old disk, is set faulty,
there is a race condition:
    1. In the first rcu protected section, resync thread did not detect
       that mreplace is set faulty and pass the condition.
    2. In the second rcu protected section, mreplace is set faulty.
    3. But, resync thread will prepare the read object first, and then
       check the write condition.
    4. It will find that mreplace is set faulty and do not have to
       prepare write object.
This cause we add resync sectors but never sub it.

[How to Reproduce]

This issue can be easily reproduced by the following steps:
    mdadm -C /dev/md0 --assume-clean -l 10 -n 4 /dev/sd[abcd]
    mdadm /dev/md0 -a /dev/sde
    mdadm /dev/md0 --replace /dev/sdd
    sleep 1
    mdadm /dev/md0 -f /dev/sde

[How to Fix]

This issue can be fixed by using local variables to record the result
of test conditions. Once the conditions are satisfied, we can make sure
that we need to issue a bio for read and a bio for write.

Previous 'commit 24afd80d99 ("md/raid10: handle recovery of
replacement devices.")' will also check whether bio is NULL, but leave
the comment saying that it is a pointless test. So we remove this dummy
check.

Reported-by: Alex Chen <alexchen@synology.com>
Reviewed-by: Allen Peng <allenpeng@synology.com>
Reviewed-by: BingJing Chang <bingjingc@synology.com>
Signed-off-by: Alex Wu <alexwu@synology.com>
Signed-off-by: Shaohua Li <shli@fb.com>
2018-09-28 11:42:47 -07:00
arch RISC-V: include linux/ftrace.h in asm-prototypes.h 2018-09-24 13:12:27 -07:00
block block: use nanosecond resolution for iostat 2018-09-21 20:26:59 -06:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto DMAengine updates for v4.19-rc1 2018-08-18 15:55:59 -07:00
Documentation media fixes for v4.19-rc5 2018-09-24 15:16:41 +02:00
drivers md/raid10: Fix raid10 replace hang when new added disk faulty 2018-09-28 11:42:47 -07:00
firmware
fs \n 2018-09-27 21:16:24 +02:00
include amd, etnaviv, mali_dp, syncobj and panel fixes 2018-09-28 18:55:17 +02:00
init Kbuild updates for v4.19 (2nd) 2018-08-25 13:40:38 -07:00
ipc ipc/shm: properly return EIDRM in shm_lock() 2018-09-04 16:45:02 -07:00
kernel Merge gitolite.kernel.org:/pub/scm/linux/kernel/git/davem/net 2018-09-25 11:19:49 +02:00
lib lib/Kconfig.debug: fix three typos in help text 2018-09-04 16:45:02 -07:00
LICENSES
mm mm: slowly shrink slabs with a relatively small number of objects 2018-09-20 22:01:11 +02:00
net ip_tunnel: be careful when accessing the inner header 2018-09-24 12:27:04 -07:00
samples
scripts linux-kselftest-4.19-rc5 2018-09-17 07:24:28 +02:00
security Revert "uapi/linux/keyctl.h: don't use C++ reserved keyword as a struct member name" 2018-09-25 13:28:58 +02:00
sound ASoC: Fixes for v4.19 2018-09-17 18:59:21 +02:00
tools Merge gitolite.kernel.org:/pub/scm/linux/kernel/git/davem/net 2018-09-25 11:19:49 +02:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: Remove obsolete kvm_unmap_hva notifier backend 2018-09-07 15:06:02 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild
Kconfig
MAINTAINERS pci-v4.19-fixes-2 2018-09-28 18:20:41 +02:00
Makefile Linux 4.19-rc5 2018-09-23 19:15:18 +02:00
README

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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.