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Jens Axboe 4ce784e8d2 io_uring: fix min_wait wakeups for SQPOLL 
Commit e15cb2200b upstream.

Using min_wait, two timeouts are given:

1) The min_wait timeout, within which up to 'wait_nr' events are
   waited for.
2) The overall long timeout, which is entered if no events are generated
   in the min_wait window.

If the min_wait has expired, any event being posted must wake the task.
For SQPOLL, that isn't the case, as it won't trigger the io_has_work()
condition, as it will have already processed the task_work that happened
when an event was posted. This causes any event to trigger post the
min_wait to not always cause the waiting application to wakeup, and
instead it will wait until the overall timeout has expired. This can be
shown in a test case that has a 1 second min_wait, with a 5 second
overall wait, even if an event triggers after 1.5 seconds:

axboe@m2max-kvm /d/iouring-mre (master)> zig-out/bin/iouring
info: MIN_TIMEOUT supported: true, features: 0x3ffff
info: Testing: min_wait=1000ms, timeout=5s, wait_nr=4
info: 1 cqes in 5000.2ms

where the expected result should be:

axboe@m2max-kvm /d/iouring-mre (master)> zig-out/bin/iouring
info: MIN_TIMEOUT supported: true, features: 0x3ffff
info: Testing: min_wait=1000ms, timeout=5s, wait_nr=4
info: 1 cqes in 1500.3ms

When the min_wait timeout triggers, reset the number of completions
needed to wake the task. This should ensure that any future events will
wake the task, regardless of how many events it originally wanted to
wait for.

Reported-by: Tip ten Brink <tip@tenbrinkmeijs.com>
Cc: stable@vger.kernel.org
Fixes: 1100c4a265 ("io_uring: add support for batch wait timeout")
Link: https://github.com/axboe/liburing/issues/1477
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit e15cb2200b)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2026-01-08 10:14:25 +01:00
arch s390/ipl: Clear SBP flag when bootprog is set 2026-01-08 10:14:25 +01:00
block block: rate-limit capacity change info log 2026-01-08 10:14:14 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: asymmetric_keys - prevent overflow in asymmetric_key_generate_id 2025-12-18 13:54:47 +01:00
Documentation nfsd: rename nfsd_serv_ prefixed methods and variables with nfsd_net_ 2026-01-08 10:14:09 +01:00
drivers gpio: regmap: Fix memleak in error path in gpio_regmap_register() 2026-01-08 10:14:25 +01:00
fs btrfs: don't log conflicting inode if it's a dir moved in the current transaction 2026-01-08 10:14:25 +01:00
include media: v4l2-mem2mem: Fix outdated documentation 2026-01-08 10:14:16 +01:00
init init: handle bootloader identifier in kernel parameters 2025-10-19 16:33:50 +02:00
io_uring io_uring: fix min_wait wakeups for SQPOLL 2026-01-08 10:14:25 +01:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:11:22 +01:00
kernel tracing: Do not register unsupported perf events 2026-01-08 10:14:23 +01:00
lib lib/vsprintf: Check pointer before dereferencing in time_and_date() 2025-12-18 13:54:57 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm shmem: fix recovery on rename failures 2026-01-08 10:13:54 +01:00
net SUNRPC: svcauth_gss: avoid NULL deref on zero length gss_token in gss_read_proxy_verf 2026-01-08 10:14:25 +01:00
rust rust: kbuild: workaround rustdoc doctests modifier bug 2025-11-24 10:36:07 +01:00
samples samples: work around glibc redefining some of our defines wrong 2025-12-12 18:37:21 +01:00
scripts kbuild: Use objtree for module signing key path 2026-01-08 10:13:56 +01:00
security KEYS: trusted: Fix a memory leak in tpm2_load_cmd 2026-01-08 10:14:13 +01:00
sound ASoC: ak4458: remove the reset operation in probe and remove 2026-01-08 10:14:08 +01:00
tools tools/testing/nvdimm: Use per-DIMM device handle 2026-01-08 10:14:20 +01:00
usr kbuild: uapi: Strip comments before size type check 2025-11-13 15:34:35 -05:00
virt KVM: Disallow toggling KVM_MEM_GUEST_MEMFD on an existing memslot 2026-01-08 10:14:21 +01:00
.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 staging: rtl8712: Remove driver using deprecated API wext 2025-12-07 06:25:02 +09:00
Makefile Linux 6.12.63 2025-12-18 13:55:23 +01:00
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.