Revision 0dd1e3773ae8afc4bfdce782bdeffc10f9cae6ec authored by Jan Stancek on 22 December 2019, 12:33:24 UTC, committed by Linus Torvalds on 22 December 2019, 17:47:47 UTC
LTP pipeio_1 test is hanging with v5.5-rc2-385-gb8e382a185eb,
with read side observing empty pipe and sleeping and write
side running out of space and then sleeping as well. In this
scenario there are 5 writers and 1 reader.
Problem is that after pipe_write() reacquires pipe lock, it
re-checks for empty pipe with potentially stale 'head' and
doesn't wake up read side anymore. pipe->tail can advance
beyond 'head', because there are multiple writers.
Use pipe->head for empty pipe check after reacquiring lock
to observe current state.
Testing: With patch, LTP pipeio_1 ran successfully in loop for 1 hour.
Without patch it hanged within a minute.
Fixes: 1b6b26ae7053 ("pipe: fix and clarify pipe write wakeup logic")
Reported-by: Rachel Sibley <rasibley@redhat.com>
Signed-off-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent b8e382a
Kconfig
# SPDX-License-Identifier: GPL-2.0
#
# For a description of the syntax of this configuration file,
# see Documentation/kbuild/kconfig-language.rst.
#
mainmenu "Linux/$(ARCH) $(KERNELVERSION) Kernel Configuration"
comment "Compiler: $(CC_VERSION_TEXT)"
source "scripts/Kconfig.include"
source "init/Kconfig"
source "kernel/Kconfig.freezer"
source "fs/Kconfig.binfmt"
source "mm/Kconfig"
source "net/Kconfig"
source "drivers/Kconfig"
source "fs/Kconfig"
source "security/Kconfig"
source "crypto/Kconfig"
source "lib/Kconfig"
source "lib/Kconfig.debug"
source "Documentation/Kconfig"
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