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Filename Latest commit message Latest commit date
Coly Li e9e93fdfce dm thin: fix deadlock when swapping to thin device
commit 9bbf5feecc7eab2c370496c1c161bbfe62084028 upstream.

This is an already known issue that dm-thin volume cannot be used as
swap, otherwise a deadlock may happen when dm-thin internal memory
demand triggers swap I/O on the dm-thin volume itself.

But thanks to commit a666e5c05e7c ("dm: fix deadlock when swapping to
encrypted device"), the limit_swap_bios target flag can also be used
for dm-thin to avoid the recursive I/O when it is used as swap.

Fix is to simply set ti->limit_swap_bios to true in both pool_ctr()
and thin_ctr().

In my test, I create a dm-thin volume /dev/vg/swap and use it as swap
device. Then I run fio on another dm-thin volume /dev/vg/main and use
large --blocksize to trigger swap I/O onto /dev/vg/swap.

The following fio command line is used in my test,
  fio --name recursive-swap-io --lockmem 1 --iodepth 128 \
     --ioengine libaio --filename /dev/vg/main --rw randrw \
    --blocksize 1M --numjobs 32 --time_based --runtime=12h

Without this fix, the whole system can be locked up within 15 seconds.

With this fix, there is no any deadlock or hung task observed after
2 hours of running fio.

Furthermore, if blocksize is changed from 1M to 128M, after around 30
seconds fio has no visible I/O, and the out-of-memory killer message
shows up in kernel message. After around 20 minutes all fio processes
are killed and the whole system is back to being alive.

This is exactly what is expected when recursive I/O happens on dm-thin
volume when it is used as swap.

Depends-on: a666e5c05e7c ("dm: fix deadlock when swapping to encrypted device")
Cc: stable@vger.kernel.org
Signed-off-by: Coly Li <colyli@suse.de>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-04-05 11:16:40 +02:00
arch sh: sanitize the flags on sigreturn 2023-04-05 11:16:40 +02:00
block blk-iocost: fix divide by 0 error in calc_lcoefs() 2023-03-11 16:43:54 +01:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:11:22 +02:00
crypto crypto: rsa-pkcs1pad - Use akcipher_request_complete 2023-03-11 16:43:41 +01:00
Documentation docs: Correct missing "d_" prefix for dentry_operations member d_weak_revalidate 2023-03-22 13:28:03 +01:00
drivers dm thin: fix deadlock when swapping to thin device 2023-04-05 11:16:40 +02:00
fs fsverity: Remove WQ_UNBOUND from fsverity read workqueue 2023-04-05 11:16:40 +02:00
include nvme-tcp: fix nvme_tcp_term_pdu to match spec 2023-04-05 11:16:38 +02:00
init init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash 2022-12-08 11:22:59 +01:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:23:06 +01:00
kernel bpf: Adjust insufficient default bpf_jit_limit 2023-04-05 11:16:37 +02:00
lib lib/mpi: Fix buffer overrun when SG is too long 2023-03-11 16:43:38 +01:00
LICENSES
mm mm/thp: check and bail out if page in deferred queue already 2023-03-11 16:44:05 +01:00
net erspan: do not use skb_mac_header() in ndo_start_xmit() 2023-04-05 11:16:38 +02:00
samples samples: vfio-mdev: Fix missing pci_disable_device() in mdpy_fb_probe() 2023-01-18 11:41:26 +01:00
scripts ftrace/scripts: Update the instructions for ftrace-bisect.sh 2023-02-06 07:52:44 +01:00
security keys: Do not cache key in task struct if key is requested from kernel thread 2023-04-05 11:16:37 +02:00
sound ALSA: hda: Match only Intel devices with CONTROLLER_IN_GPU() 2023-03-22 13:28:04 +01:00
tools selftests/bpf: check that modifier resolves after pointer 2023-04-05 11:16:39 +02:00
usr
virt KVM: Destroy target device if coalesced MMIO unregistration fails 2023-03-11 16:44:01 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS net/phy/mdio-i2c: Move header file to include/linux/mdio 2023-02-06 07:52:46 +01:00
Makefile Linux 5.4.239 2023-03-30 15:04:27 +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.

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.