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Sandeep Dhavale 597fb60c75 erofs: Fix detection of atomic context [ Upstream commit `12d0a24afd` ] Current check for atomic context is not sufficient as z_erofs_decompressqueue_endio can be called under rcu lock from blk_mq_flush_plug_list(). See the stacktrace [1] In such case we should hand off the decompression work for async processing rather than trying to do sync decompression in current context. Patch fixes the detection by checking for rcu_read_lock_any_held() and while at it use more appropriate !in_task() check than in_atomic(). Background: Historically erofs would always schedule a kworker for decompression which would incur the scheduling cost regardless of the context. But z_erofs_decompressqueue_endio() may not always be in atomic context and we could actually benefit from doing the decompression in z_erofs_decompressqueue_endio() if we are in thread context, for example when running with dm-verity. This optimization was later added in patch [2] which has shown improvement in performance benchmarks. ============================================== [1] Problem stacktrace [name:core&]BUG: sleeping function called from invalid context at kernel/locking/mutex.c:291 [name:core&]in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 1615, name: CpuMonitorServi [name:core&]preempt_count: 0, expected: 0 [name:core&]RCU nest depth: 1, expected: 0 CPU: 7 PID: 1615 Comm: CpuMonitorServi Tainted: G S W OE 6.1.25-android14-5-maybe-dirty-mainline #1 Hardware name: MT6897 (DT) Call trace: dump_backtrace+0x108/0x15c show_stack+0x20/0x30 dump_stack_lvl+0x6c/0x8c dump_stack+0x20/0x48 __might_resched+0x1fc/0x308 __might_sleep+0x50/0x88 mutex_lock+0x2c/0x110 z_erofs_decompress_queue+0x11c/0xc10 z_erofs_decompress_kickoff+0x110/0x1a4 z_erofs_decompressqueue_endio+0x154/0x180 bio_endio+0x1b0/0x1d8 __dm_io_complete+0x22c/0x280 clone_endio+0xe4/0x280 bio_endio+0x1b0/0x1d8 blk_update_request+0x138/0x3a4 blk_mq_plug_issue_direct+0xd4/0x19c blk_mq_flush_plug_list+0x2b0/0x354 __blk_flush_plug+0x110/0x160 blk_finish_plug+0x30/0x4c read_pages+0x2fc/0x370 page_cache_ra_unbounded+0xa4/0x23c page_cache_ra_order+0x290/0x320 do_sync_mmap_readahead+0x108/0x2c0 filemap_fault+0x19c/0x52c __do_fault+0xc4/0x114 handle_mm_fault+0x5b4/0x1168 do_page_fault+0x338/0x4b4 do_translation_fault+0x40/0x60 do_mem_abort+0x60/0xc8 el0_da+0x4c/0xe0 el0t_64_sync_handler+0xd4/0xfc el0t_64_sync+0x1a0/0x1a4 [2] Link: https://lore.kernel.org/all/20210317035448.13921-1-huangjianan@oppo.com/ Reported-by: Will Shiu <Will.Shiu@mediatek.com> Suggested-by: Gao Xiang <xiang@kernel.org> Signed-off-by: Sandeep Dhavale <dhavale@google.com> Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com> Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com> Link: https://lore.kernel.org/r/20230621220848.3379029-1-dhavale@google.com Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com> Signed-off-by: Sasha Levin <sashal@kernel.org>		History 2023-07-27 08:56:46 +02:00
arch	MIPS: dec: prom: Address -Warray-bounds warning	2023-07-27 08:56:44 +02:00
block	blk-mq: fix NULL dereference on q->elevator in blk_mq_elv_switch_none	2023-07-27 08:56:45 +02:00
certs	KEYS: Add missing function documentation	2023-04-24 16:15:52 +03:00
crypto	crypto: jitter - correct health test during initialization	2023-07-19 16:36:19 +02:00
Documentation	media: uapi: Fix [GS]_ROUTING ACTIVE flag value	2023-07-23 13:54:08 +02:00
drivers	scsi: sg: fix blktrace debugfs entries leakage	2023-07-27 08:56:45 +02:00
fs	erofs: Fix detection of atomic context	2023-07-27 08:56:46 +02:00
include	posix-timers: Ensure timer ID search-loop limit is valid	2023-07-27 08:56:45 +02:00
init	kbuild: Fix CFI failures with GCOV	2023-07-19 16:36:23 +02:00
io_uring	io_uring: Fix io_uring mmap() by using architecture-provided get_unmapped_area()	2023-07-27 08:56:31 +02:00
ipc	Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2023-02-24 19:20:07 -08:00
kernel	posix-timers: Ensure timer ID search-loop limit is valid	2023-07-27 08:56:45 +02:00
lib	maple_tree: set the node limit when creating a new root node	2023-07-27 08:56:32 +02:00
LICENSES	LICENSES: Add the copyleft-next-0.3.1 license	2022-11-08 15:44:01 +01:00
mm	mm/mlock: fix vma iterator conversion of apply_vma_lock_flags()	2023-07-27 08:56:32 +02:00
net	can: bcm: Fix UAF in bcm_proc_show()	2023-07-27 08:56:36 +02:00
rust	Rust changes for v6.4	2023-04-30 11:20:22 -07:00
samples	samples: ftrace: Save required argument registers in sample trampolines	2023-07-23 13:54:09 +02:00
scripts	kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS	2023-07-19 16:37:00 +02:00
security	keys: Fix linking a duplicate key to a keyring's assoc_array	2023-07-27 08:56:32 +02:00
sound	ALSA: hda/realtek: Add quirks for ROG ALLY CS35l41 audio	2023-07-27 08:56:44 +02:00
tools	selftests: tc: add ConnTrack procfs kconfig	2023-07-27 08:56:37 +02:00
usr	initramfs: Check negative timestamp to prevent broken cpio archive	2023-04-16 17:37:01 +09:00
virt	KVM: Avoid illegal stage2 mapping on invalid memory slot	2023-06-22 15:14:57 -04:00
.clang-format	cxl for v6.4	2023-04-30 11:51:51 -07:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.get_maintainer.ignore	get_maintainer: add Alan to .get_maintainer.ignore	2022-08-20 15:17:44 -07:00
.gitattributes	.gitattributes: use 'dts' diff driver for *.dtso files	2023-02-26 15:28:23 +09:00
.gitignore	linux-kselftest-kunit-6.4-rc1	2023-04-24 12:31:32 -07:00
.mailmap	mailmap: add entries for Ben Dooks	2023-06-19 13:19:35 -07:00
.rustfmt.toml	rust: add `.rustfmt.toml`	2022-09-28 09:02:20 +02:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	MAINTAINERS: sctp: move Neil to CREDITS	2023-05-12 08:51:32 +01:00
Kbuild	Kbuild updates for v6.1	2022-10-10 12:00:45 -07:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	Networking fixes for 6.4-rc8, including fixes from ipsec, bpf,	2023-06-22 17:59:51 -07:00
Makefile	Linux 6.4.6	2023-07-24 18:56:41 +02:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00

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.