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Zhihao Cheng 9a9dc60da7 fs-writeback: writeback_sb_inodes：Recalculate 'wrote' according skipped pages commit `68f4c6eba7` upstream. Commit `505a666ee3` ("writeback: plug writeback in wb_writeback() and writeback_inodes_wb()") has us holding a plug during wb_writeback, which may cause a potential ABBA dead lock: wb_writeback fat_file_fsync blk_start_plug(&plug) for (;;) { iter i-1: some reqs have been added into plug->mq_list // LOCK A iter i: progress = __writeback_inodes_wb(wb, work) . writeback_sb_inodes // fat's bdev . __writeback_single_inode . . generic_writepages . . __block_write_full_page . . . . __generic_file_fsync . . . . sync_inode_metadata . . . . writeback_single_inode . . . . __writeback_single_inode . . . . fat_write_inode . . . . __fat_write_inode . . . . sync_dirty_buffer // fat's bdev . . . . lock_buffer(bh) // LOCK B . . . . submit_bh . . . . blk_mq_get_tag // LOCK A . . . trylock_buffer(bh) // LOCK B . . . redirty_page_for_writepage . . . wbc->pages_skipped++ . . --wbc->nr_to_write . wrote += write_chunk - wbc.nr_to_write // wrote > 0 . requeue_inode . redirty_tail_locked if (progress) // progress > 0 continue; iter i+1: queue_io // similar process with iter i, infinite for-loop ! } blk_finish_plug(&plug) // flush plug won't be called Above process triggers a hungtask like: [ 399.044861] INFO: task bb:2607 blocked for more than 30 seconds. [ 399.046824] Not tainted 5.18.0-rc1-00005-gefae4d9eb6a2-dirty [ 399.051539] task:bb state:D stack: 0 pid: 2607 ppid: 2426 flags:0x00004000 [ 399.051556] Call Trace: [ 399.051570] __schedule+0x480/0x1050 [ 399.051592] schedule+0x92/0x1a0 [ 399.051602] io_schedule+0x22/0x50 [ 399.051613] blk_mq_get_tag+0x1d3/0x3c0 [ 399.051640] __blk_mq_alloc_requests+0x21d/0x3f0 [ 399.051657] blk_mq_submit_bio+0x68d/0xca0 [ 399.051674] __submit_bio+0x1b5/0x2d0 [ 399.051708] submit_bio_noacct+0x34e/0x720 [ 399.051718] submit_bio+0x3b/0x150 [ 399.051725] submit_bh_wbc+0x161/0x230 [ 399.051734] __sync_dirty_buffer+0xd1/0x420 [ 399.051744] sync_dirty_buffer+0x17/0x20 [ 399.051750] __fat_write_inode+0x289/0x310 [ 399.051766] fat_write_inode+0x2a/0xa0 [ 399.051783] __writeback_single_inode+0x53c/0x6f0 [ 399.051795] writeback_single_inode+0x145/0x200 [ 399.051803] sync_inode_metadata+0x45/0x70 [ 399.051856] __generic_file_fsync+0xa3/0x150 [ 399.051880] fat_file_fsync+0x1d/0x80 [ 399.051895] vfs_fsync_range+0x40/0xb0 [ 399.051929] __x64_sys_fsync+0x18/0x30 In my test, 'need_resched()' (which is imported by `590dca3a71` "fs-writeback: unplug before cond_resched in writeback_sb_inodes") in function 'writeback_sb_inodes()' seldom comes true, unless cond_resched() is deleted from write_cache_pages(). Fix it by correcting wrote number according number of skipped pages in writeback_sb_inodes(). Goto Link to find a reproducer. Link: https://bugzilla.kernel.org/show_bug.cgi?id=215837 Cc: stable@vger.kernel.org # v4.3 Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220510133805.1988292-1-chengzhihao1@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2022-06-09 10:21:22 +02:00
arch	powerpc/fsl_rio: Fix refcount leak in fsl_rio_setup	2022-06-09 10:21:18 +02:00
block	block-map: add __GFP_ZERO flag for alloc_page in function bio_copy_kern	2022-05-12 12:25:45 +02:00
certs	certs: Trigger creation of RSA module signing key if it's not an RSA key	2021-09-15 09:50:29 +02:00
crypto	crypto: cryptd - Protect per-CPU resource by disabling BH.	2022-06-09 10:21:17 +02:00
Documentation	spi: qcom-qspi: Add minItems to interconnect-names	2022-06-09 10:20:59 +02:00
drivers	iwlwifi: mvm: fix assert 1F04 upon reconfig	2022-06-09 10:21:22 +02:00
fs	fs-writeback: writeback_sb_inodes：Recalculate 'wrote' according skipped pages	2022-06-09 10:21:22 +02:00
include	mailbox: forward the hrtimer if not queued and under a lock	2022-06-09 10:21:18 +02:00
init	random: handle latent entropy and command line from random_init()	2022-05-30 09:33:44 +02:00
ipc	ipc/mqueue: use get_tree_nodev() in mqueue_get_tree()	2022-06-09 10:21:17 +02:00
kernel	sched/fair: Fix cfs_rq_clock_pelt() for throttled cfs_rq	2022-06-09 10:21:02 +02:00
lib	lib/crypto: add prompts back to crypto libraries	2022-06-06 08:42:42 +02:00
LICENSES
mm	zsmalloc: fix races between asynchronous zspage free and page migration	2022-06-06 08:42:43 +02:00
net	wifi: mac80211: fix use-after-free in chanctx code	2022-06-09 10:21:22 +02:00
samples	samples/bpf, xdpsock: Fix race when running for fix duration of time	2022-04-08 14:40:21 +02:00
scripts	scripts/faddr2line: Fix overlapping text section failures	2022-06-09 10:21:08 +02:00
security	lsm,selinux: pass flowi_common instead of flowi to the LSM hooks	2022-06-09 10:21:09 +02:00
sound	ASoC: atmel-classd: Remove endianness flag on class d component	2022-06-09 10:21:16 +02:00
tools	perf jevents: Fix event syntax error caused by ExtSel	2022-06-09 10:21:21 +02:00
usr	usr/include/Makefile: add linux/nfc.h to the compile-test coverage	2022-02-01 17:25:48 +01:00
virt	KVM: Prevent module exit until all VMs are freed	2022-04-08 14:40:38 +02:00
.clang-format	RDMA 5.10 pull request	2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore	kbuild: generate Module.symvers only when vmlinux exists	2021-05-19 10:12:59 +02:00
.mailmap	mailmap: add two more addresses of Uwe Kleine-König	2020-12-06 10:19:07 -08:00
COPYING
CREDITS	MAINTAINERS: Move Jason Cooper to CREDITS	2020-11-30 10:20:34 +01:00
Kbuild
Kconfig
MAINTAINERS	MAINTAINERS: add git tree for random.c	2022-05-30 09:33:24 +02:00
Makefile	Linux 5.10.120	2022-06-06 08:42:45 +02:00
README

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.