linux

mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-10-16 22:39:48 +00:00

No description

C 96.9%
Assembly 0.9%
Rust 0.6%
Shell 0.6%
Python 0.5%
Other 0.3%

Find a file

Bodo Stroesser b4150b6881 scsi: target: tcmu: Fix xarray RCU warning Commit `f5ce815f34` ("scsi: target: tcmu: Support DATA_BLOCK_SIZE = N * PAGE_SIZE") introduced xas_next() calls to iterate xarray elements. These calls triggered the WARNING "suspicious RCU usage" at tcmu device set up [1]. In the call stack of xas_next(), xas_load() was called. According to its comment, this function requires "the xa_lock or the RCU lock". To avoid the warning: - Guard the small loop calling xas_next() in tcmu_get_empty_block with RCU lock. - In the large loop in tcmu_copy_data using RCU lock would possibly disable preemtion for a long time (copy multi MBs). Therefore replace XA_STATE, xas_set and xas_next with a single xa_load. [1] [ 1899.867091] ============================= [ 1899.871199] WARNING: suspicious RCU usage [ 1899.875310] 5.13.0-rc1+ #41 Not tainted [ 1899.879222] ----------------------------- [ 1899.883299] include/linux/xarray.h:1182 suspicious rcu_dereference_check() usage! [ 1899.890940] other info that might help us debug this: [ 1899.899082] rcu_scheduler_active = 2, debug_locks = 1 [ 1899.905719] 3 locks held by kworker/0:1/1368: [ 1899.910161] #0: ffffa1f8c8b98738 ((wq_completion)target_submission){+.+.}-{0:0}, at: process_one_work+0x1ee/0x580 [ 1899.920732] #1: ffffbd7040cd7e78 ((work_completion)(&q->sq.work)){+.+.}-{0:0}, at: process_one_work+0x1ee/0x580 [ 1899.931146] #2: ffffa1f8d1c99768 (&udev->cmdr_lock){+.+.}-{3:3}, at: tcmu_queue_cmd+0xea/0x160 [target_core_user] [ 1899.941678] stack backtrace: [ 1899.946093] CPU: 0 PID: 1368 Comm: kworker/0:1 Not tainted 5.13.0-rc1+ #41 [ 1899.953070] Hardware name: System manufacturer System Product Name/PRIME Z270-A, BIOS 1302 03/15/2018 [ 1899.962459] Workqueue: target_submission target_queued_submit_work [target_core_mod] [ 1899.970337] Call Trace: [ 1899.972839] dump_stack+0x6d/0x89 [ 1899.976222] xas_descend+0x10e/0x120 [ 1899.979875] xas_load+0x39/0x50 [ 1899.983077] tcmu_get_empty_blocks+0x115/0x1c0 [target_core_user] [ 1899.989318] queue_cmd_ring+0x1da/0x630 [target_core_user] [ 1899.994897] ? rcu_read_lock_sched_held+0x3f/0x70 [ 1899.999695] ? trace_kmalloc+0xa6/0xd0 [ 1900.003501] ? __kmalloc+0x205/0x380 [ 1900.007167] tcmu_queue_cmd+0x12f/0x160 [target_core_user] [ 1900.012746] __target_execute_cmd+0x23/0xa0 [target_core_mod] [ 1900.018589] transport_generic_new_cmd+0x1f3/0x370 [target_core_mod] [ 1900.025046] transport_handle_cdb_direct+0x34/0x50 [target_core_mod] [ 1900.031517] target_queued_submit_work+0x43/0xe0 [target_core_mod] [ 1900.037837] process_one_work+0x268/0x580 [ 1900.041952] ? process_one_work+0x580/0x580 [ 1900.046195] worker_thread+0x55/0x3b0 [ 1900.049921] ? process_one_work+0x580/0x580 [ 1900.054192] kthread+0x143/0x160 [ 1900.057499] ? kthread_create_worker_on_cpu+0x40/0x40 [ 1900.062661] ret_from_fork+0x1f/0x30 Link: https://lore.kernel.org/r/20210519135440.26773-1-bostroesser@gmail.com Fixes: `f5ce815f34` ("scsi: target: tcmu: Support DATA_BLOCK_SIZE = N * PAGE_SIZE") Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> Signed-off-by: Bodo Stroesser <bostroesser@gmail.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>		History 2021-05-21 16:15:48 -04:00
arch	Handle power-gating of AMD IOMMU perf counters properly when they are used.	2021-05-09 13:00:26 -07:00
block	block-5.13-2021-05-09	2021-05-09 13:25:14 -07:00
certs	Kbuild updates for v5.13 (2nd)	2021-05-08 10:00:11 -07:00
crypto	for-5.13/drivers-2021-04-27	2021-04-28 14:39:37 -07:00
Documentation	A set of scheduler updates:	2021-05-09 13:14:34 -07:00
drivers	scsi: target: tcmu: Fix xarray RCU warning	2021-05-21 16:15:48 -04:00
fs	3 small SMB3 chmultichannel related changesets (also for stable)	2021-05-09 13:19:29 -07:00
include	block-5.13-2021-05-09	2021-05-09 13:25:14 -07:00
init	Merge branch 'akpm' (patches from Andrew)	2021-05-07 00:34:51 -07:00
ipc	ipc/sem.c: spelling fix	2021-05-07 00:26:34 -07:00
kernel	A set of scheduler updates:	2021-05-09 13:14:34 -07:00
lib	Kbuild updates for v5.13 (2nd)	2021-05-08 10:00:11 -07:00
LICENSES	LICENSES: Add the CC-BY-4.0 license	2020-12-08 10:33:27 -07:00
mm	mm: fix typos in comments	2021-05-07 00:26:35 -07:00
net	Networking fixes for 5.13-rc1, including fixes from bpf, can	2021-05-08 08:31:46 -07:00
samples	Kbuild updates for v5.13 (2nd)	2021-05-08 10:00:11 -07:00
scripts	Kbuild updates for v5.13 (2nd)	2021-05-08 10:00:11 -07:00
security	Simple code cleanup	2021-05-05 12:08:06 -07:00
sound	sound fixes for 5.13-rc1	2021-05-07 11:40:18 -07:00
tools	Kbuild updates for v5.13 (2nd)	2021-05-08 10:00:11 -07:00
usr	.gitignore: prefix local generated files with a slash	2021-05-02 00:43:35 +09:00
virt	KVM: Boost vCPU candidate in user mode which is delivering interrupt	2021-04-21 12:20:03 -04:00
.clang-format	cxl for 5.12	2021-02-24 09:38:36 -08:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.get_maintainer.ignore	Opt out of scripts/get_maintainer.pl	2019-05-16 10:53:40 -07:00
.gitattributes	.gitattributes: use 'dts' diff driver for dts files	2019-12-04 19:44:11 -08:00
.gitignore	.gitignore: ignore only top-level modules.builtin	2021-05-02 00:43:35 +09:00
.mailmap	It's been a relatively busy cycle in docsland, though more than usually	2021-04-26 13:22:43 -07:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	MAINTAINERS: move Murali Karicheri to credits	2021-04-29 15:47:30 -07:00
Kbuild	kbuild: rename hostprogs-y/always to hostprogs/always-y	2020-02-04 01:53:07 +09:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	Networking fixes for 5.13-rc1, including fixes from bpf, can	2021-05-08 08:31:46 -07:00
Makefile	Linux 5.13-rc1	2021-05-09 14:17:44 -07:00
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.