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Junli Liu cc2ec79a6c erofs: fix atomic context detection when !CONFIG_DEBUG_LOCK_ALLOC [ Upstream commit `c99fab6e80` ] Since EROFS handles decompression in non-atomic contexts due to uncontrollable decompression latencies and vmap() usage, it tries to detect atomic contexts and only kicks off a kworker on demand in order to reduce unnecessary scheduling overhead. However, the current approach is insufficient and can lead to sleeping function calls in invalid contexts, causing kernel warnings and potential system instability. See the stacktrace [1] and previous discussion [2]. The current implementation only checks rcu_read_lock_any_held(), which behaves inconsistently across different kernel configurations: - When CONFIG_DEBUG_LOCK_ALLOC is enabled: correctly detects RCU critical sections by checking rcu_lock_map - When CONFIG_DEBUG_LOCK_ALLOC is disabled: compiles to "!preemptible()", which only checks preempt_count and misses RCU critical sections This patch introduces z_erofs_in_atomic() to provide comprehensive atomic context detection: 1. Check RCU preemption depth when CONFIG_PREEMPTION is enabled, as RCU critical sections may not affect preempt_count but still require atomic handling 2. Always use async processing when CONFIG_PREEMPT_COUNT is disabled, as preemption state cannot be reliably determined 3. Fall back to standard preemptible() check for remaining cases The function replaces the previous complex condition check and ensures that z_erofs always uses (kthread_)work in atomic contexts to minimize scheduling overhead and prevent sleeping in invalid contexts. [1] Problem stacktrace [ 61.266692] BUG: sleeping function called from invalid context at kernel/locking/rtmutex_api.c:510 [ 61.266702] in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 107, name: irq/54-ufshcd [ 61.266704] preempt_count: 0, expected: 0 [ 61.266705] RCU nest depth: 2, expected: 0 [ 61.266710] CPU: 0 UID: 0 PID: 107 Comm: irq/54-ufshcd Tainted: G W O 6.12.17 #1 [ 61.266714] Tainted: [W]=WARN, [O]=OOT_MODULE [ 61.266715] Hardware name: schumacher (DT) [ 61.266717] Call trace: [ 61.266718] dump_backtrace+0x9c/0x100 [ 61.266727] show_stack+0x20/0x38 [ 61.266728] dump_stack_lvl+0x78/0x90 [ 61.266734] dump_stack+0x18/0x28 [ 61.266736] __might_resched+0x11c/0x180 [ 61.266743] __might_sleep+0x64/0xc8 [ 61.266745] mutex_lock+0x2c/0xc0 [ 61.266748] z_erofs_decompress_queue+0xe8/0x978 [ 61.266753] z_erofs_decompress_kickoff+0xa8/0x190 [ 61.266756] z_erofs_endio+0x168/0x288 [ 61.266758] bio_endio+0x160/0x218 [ 61.266762] blk_update_request+0x244/0x458 [ 61.266766] scsi_end_request+0x38/0x278 [ 61.266770] scsi_io_completion+0x4c/0x600 [ 61.266772] scsi_finish_command+0xc8/0xe8 [ 61.266775] scsi_complete+0x88/0x148 [ 61.266777] blk_mq_complete_request+0x3c/0x58 [ 61.266780] scsi_done_internal+0xcc/0x158 [ 61.266782] scsi_done+0x1c/0x30 [ 61.266783] ufshcd_compl_one_cqe+0x12c/0x438 [ 61.266786] __ufshcd_transfer_req_compl+0x2c/0x78 [ 61.266788] ufshcd_poll+0xf4/0x210 [ 61.266789] ufshcd_transfer_req_compl+0x50/0x88 [ 61.266791] ufshcd_intr+0x21c/0x7c8 [ 61.266792] irq_forced_thread_fn+0x44/0xd8 [ 61.266796] irq_thread+0x1a4/0x358 [ 61.266799] kthread+0x12c/0x138 [ 61.266802] ret_from_fork+0x10/0x20 [2] https://lore.kernel.org/r/58b661d0-0ebb-4b45-a10d-c5927fb791cd@paulmck-laptop Signed-off-by: Junli Liu <liujunli@lixiang.com> Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com> Link: https://lore.kernel.org/r/20250805011957.911186-1-liujunli@lixiang.com [ Gao Xiang: Use the original trace in v1. ] Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com> Signed-off-by: Sasha Levin <sashal@kernel.org>		History 2025-09-04 15:31:44 +02:00
arch	mips: lantiq: xway: sysctrl: rename the etop node	2025-09-04 15:31:43 +02:00
block	block: Introduce bio_needs_zone_write_plugging()	2025-08-20 18:30:51 +02:00
certs	sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3	2024-09-20 19:52:48 +03:00
crypto	crypto: jitter - fix intermediary handling	2025-08-20 18:30:42 +02:00
Documentation	mptcp: disable add_addr retransmission when timeout is 0	2025-08-28 16:31:07 +02:00
drivers	scsi: core: sysfs: Correct sysfs attributes access rights	2025-09-04 15:31:43 +02:00
fs	erofs: fix atomic context detection when !CONFIG_DEBUG_LOCK_ALLOC	2025-09-04 15:31:44 +02:00
include	vhost: Fix ioctl # for VHOST_[GS]ET_FORK_FROM_OWNER	2025-09-04 15:31:43 +02:00
init	io_uring: fix breakage in EXPERT menu	2025-08-15 12:13:32 +02:00
io_uring	io_uring/futex: ensure io_futex_wait() cleans up properly on failure	2025-08-28 16:31:05 +02:00
ipc	ipc: fix to protect IPCS lookups using RCU	2025-06-27 11:11:22 +01:00
kernel	ftrace: Fix potential warning in trace_printk_seq during ftrace_dump	2025-09-04 15:31:43 +02:00
lib	lib/sbitmap: convert shallow_depth from one word to the whole sbitmap	2025-08-20 18:30:49 +02:00
LICENSES	LICENSES: add 0BSD license text	2024-09-01 20:43:24 -07:00
mm	mm/memory-failure: fix infinite UCE for VM_PFNMAP pfn	2025-08-28 16:31:05 +02:00
net	netfilter: nf_reject: don't leak dst refcount for loopback packets	2025-08-28 16:31:16 +02:00
rust	rust: alloc: fix `rusttest` by providing `Cmalloc::aligned_layout` too	2025-08-28 16:31:13 +02:00
samples	samples: mei: Fix building on musl libc	2025-08-15 12:13:38 +02:00
scripts	kconfig: lxdialog: fix 'space' to (de)select options	2025-08-20 18:30:48 +02:00
security	apparmor: Fix 8-byte alignment for initial dfa blob streams	2025-08-28 16:30:56 +02:00
sound	ASoC: codecs: tx-macro: correct tx_macro_component_drv name	2025-09-04 15:31:44 +02:00
tools	perf symbol-minimal: Fix ehdr reading in filename__read_build_id	2025-09-04 15:31:43 +02:00
usr	kbuild: hdrcheck: fix cross build with clang	2025-03-13 13:02:18 +01:00
virt	KVM: Allow CPU to reschedule while setting per-page memory attributes	2025-07-17 18:37:08 +02:00
.clang-format	clang-format: Update with v6.11-rc1's `for_each` macro list	2024-08-02 13:20:31 +02:00
.clippy.toml	rust: give Clippy the minimum supported Rust version	2025-08-01 09:48:44 +01:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.editorconfig	.editorconfig: remove trim_trailing_whitespace option	2024-06-13 16:47:52 +02:00
.get_maintainer.ignore	Add Jeff Kirsher to .get_maintainer.ignore	2024-03-08 11:36:54 +00:00
.gitattributes	.gitattributes: set diff driver for Rust source code files	2023-05-31 17:48:25 +02:00
.gitignore	rust: introduce `.clippy.toml`	2025-03-13 13:01:42 +01:00
.mailmap	mailmap: add entry for Thorsten Blum	2024-11-07 14:14:59 -08:00
.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: Remove self from DSA entry	2024-11-03 12:52:38 -08:00
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	MAINTAINERS: Update Alexey Makhalov's email address	2025-05-22 14:29:46 +02:00
Makefile	Linux 6.12.44	2025-08-28 16:31:16 +02:00
README	README: Fix spelling	2024-03-18 03:36:32 -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 reStructuredText 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.