Hello stable team,
Please consider applying the following 2 patches to Linux-4.4 stable tree. The patches fix regression introduced in 3.14 where both read and write started to run under lock taken, which resulted in FUSE (and many other drivers) deadlocks for cases where stream-like files are used with read and write being run simultaneously.
Please see complete problem description in upstream commit 10dce8af3422 ("fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock").
The actual FUSE fix (upstream commit bbd84f33652f "fuse: Add FOPEN_STREAM to use stream_open()") was merged into 5.2 with `Cc: stable@vger.kernel.org # v3.14+` mark and is already included into 5.1, 5.0 and 4.19 stable trees. However for some reason it is not (yet ?) included into 4.14, 4.9, 4.4, 3.18 and 3.16 trees.
The patches fix a real problem into which my FUSE filesystem ran, and which also likely affects OSSPD (full details are in the patches description). Please consider including the fixes into 4.4 (as well as into other stable trees - I'm sending corresponding series separately - - one per tree).
Thanks beforehand, Kirill
P.S. the patches have been already a bit discussed in stable context some time ago:
https://lore.kernel.org/linux-fsdevel/CAHk-=wgh234SyBG810=vB360PCzVkAhQRqGg8... https://lore.kernel.org/linux-fsdevel/20190424183012.GB3798@deco.navytux.spb... https://lore.kernel.org/linux-fsdevel/20190424191652.GE3798@deco.navytux.spb... ...
Kirill Smelkov (2): fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock fuse: Add FOPEN_STREAM to use stream_open()
drivers/xen/xenbus/xenbus_dev_frontend.c | 2 +- fs/fuse/file.c | 4 +- fs/open.c | 18 ++ fs/read_write.c | 5 +- include/linux/fs.h | 4 + include/uapi/linux/fuse.h | 2 + scripts/coccinelle/api/stream_open.cocci | 363 +++++++++++++++++++++++ 7 files changed, 394 insertions(+), 4 deletions(-) create mode 100644 scripts/coccinelle/api/stream_open.cocci