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Filename Latest commit message Latest commit date
Ming Lei 74c77d6a4e blk-mq: insert passthrough request into hctx->dispatch directly
[ Upstream commit 01e99aeca3979600302913cef3f89076786f32c8 ]

For some reason, device may be in one situation which can't handle
FS request, so STS_RESOURCE is always returned and the FS request
will be added to hctx->dispatch. However passthrough request may
be required at that time for fixing the problem. If passthrough
request is added to scheduler queue, there isn't any chance for
blk-mq to dispatch it given we prioritize requests in hctx->dispatch.
Then the FS IO request may never be completed, and IO hang is caused.

So passthrough request has to be added to hctx->dispatch directly
for fixing the IO hang.

Fix this issue by inserting passthrough request into hctx->dispatch
directly together withing adding FS request to the tail of
hctx->dispatch in blk_mq_dispatch_rq_list(). Actually we add FS request
to tail of hctx->dispatch at default, see blk_mq_request_bypass_insert().

Then it becomes consistent with original legacy IO request
path, in which passthrough request is always added to q->queue_head.

Cc: Dongli Zhang <dongli.zhang@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-03-21 08:11:52 +01:00
arch x86/mce: Fix logic and comments around MSR_PPIN_CTL 2020-03-18 07:17:54 +01:00
block blk-mq: insert passthrough request into hctx->dispatch directly 2020-03-21 08:11:52 +01:00
certs
crypto
Documentation ACPI: watchdog: Allow disabling WDAT at boot 2020-03-21 08:11:47 +01:00
drivers net: ll_temac: Handle DMA halt condition caused by buffer underrun 2020-03-21 08:11:51 +01:00
fs fscrypt: don't evict dirty inodes after removing key 2020-03-18 07:17:53 +01:00
include driver code: clarify and fix platform device DMA mask allocation 2020-03-18 07:17:56 +01:00
init
ipc
kernel tracing: Fix number printing bug in print_synth_event() 2020-03-21 08:11:49 +01:00
lib kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
LICENSES
mm net: memcg: late association of sock to memcg 2020-03-18 07:17:43 +01:00
net mac80211: rx: avoid RCU list traversal under mutex 2020-03-21 08:11:51 +01:00
samples
scripts kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
security efi: Only print errors about failing to get certs if EFI vars are found 2020-03-12 13:00:14 +01:00
sound ALSA: hda/realtek - Fixed one of HP ALC671 platform Headset Mic supported 2020-03-18 07:17:38 +01:00
tools selftests/rseq: Fix out-of-tree compilation 2020-03-21 08:11:49 +01:00
usr kbuild: fix 'No such file or directory' warning when cleaning 2020-03-12 13:00:09 +01:00
virt KVM: Check for a bad hva before dropping into the ghc slow path 2020-03-05 16:43:48 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.26 2020-03-18 07:17:59 +01:00
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.