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Filename Latest commit message Latest commit date
Vivek Goyal 2b5e027657 virtiofs: schedule blocking async replies in separate worker
[ Upstream commit bb737bbe48bea9854455cb61ea1dc06e92ce586c ]

In virtiofs (unlike in regular fuse) processing of async replies is
serialized.  This can result in a deadlock in rare corner cases when
there's a circular dependency between the completion of two or more async
replies.

Such a deadlock can be reproduced with xfstests:generic/503 if TEST_DIR ==
SCRATCH_MNT (which is a misconfiguration):

 - Process A is waiting for page lock in worker thread context and blocked
   (virtio_fs_requests_done_work()).
 - Process B is holding page lock and waiting for pending writes to
   finish (fuse_wait_on_page_writeback()).
 - Write requests are waiting in virtqueue and can't complete because
   worker thread is blocked on page lock (process A).

Fix this by creating a unique work_struct for each async reply that can
block (O_DIRECT read).

Fixes: a62a8ef9d9 ("virtio-fs: add virtiofs filesystem")
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-06-24 17:50:21 +02:00
arch ARM: dts: sun8i-h2-plus-bananapi-m2-zero: Fix led polarity 2020-06-24 17:50:20 +02:00
block iocost: don't let vrate run wild while there's no saturation signal 2020-06-22 09:31:06 +02:00
certs
crypto crypto: drbg - fix error return code in drbg_alloc_state() 2020-06-17 16:40:31 +02:00
Documentation dt-bindings: display: mediatek: control dpi pins mode to avoid leakage 2020-06-22 09:30:58 +02:00
drivers pinctrl: rza1: Fix wrong array assignment of rza1l_swio_entries 2020-06-24 17:50:21 +02:00
fs virtiofs: schedule blocking async replies in separate worker 2020-06-24 17:50:21 +02:00
include usb: gadget: core: sync interrupt before unbind the udc 2020-06-24 17:50:16 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel kernel/cpu_pm: Fix uninitted local in cpu_pm 2020-06-22 09:31:22 +02:00
lib kasan: stop tests being eliminated as dead code with FORTIFY_SOURCE 2020-06-22 09:31:12 +02:00
LICENSES
mm mm: call cond_resched() from deferred_init_memmap() 2020-06-22 09:31:14 +02:00
net bpf, sockhash: Fix memory leak when unlinking sockets in sock_hash_free 2020-06-24 17:50:19 +02:00
samples samples: bpf: Fix build error 2020-06-03 08:21:15 +02:00
scripts mksysmap: Fix the mismatch of '.L' symbols in System.map 2020-06-24 17:50:19 +02:00
security apparmor: fix nnp subset test for unconfined 2020-06-24 17:50:20 +02:00
sound ASoC: meson: add missing free_irq() in error path 2020-06-24 17:50:19 +02:00
tools perf symbols: Fix kernel maps for kcore and eBPF 2020-06-22 09:31:27 +02:00
usr
virt KVM: arm64: Save the host's PtrAuth keys in non-preemptible context 2020-06-17 16:40:38 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
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COPYING
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Kconfig
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Makefile Linux 5.4.48 2020-06-22 09:31:27 +02:00
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.