From: Ildar Kamaletdinov <i.kamaletdinov@xxxxxx> It could be impossible to freeze the fuse task in request_wait_answer() when it calls wait_event_killable() with the FR_FINISHED flag because the fuse daemon could be frozen before the task, so it simply can't finish a request. E.g. it could be impossible to freeze while doing poll() on a fuse FS: [ 90.468003] (0)[]Freezing of tasks aborted after 6.507 seconds [ 90.468793] (0)[1649:kworker/u8:18]qtaround::mt::A D [ 90.468830] 0 1590 1102 0x00400009 [ 90.468850] (0)[1649:kworker/u8:18]Call trace: [ 90.468887] (0)[1649:kworker/u8:18][<ffffff82a7685a44>] __switch_to+0xd8/0xf4 [ 90.468929] (0)[1649:kworker/u8:18][<ffffff82a851fa9c>] __schedule+0x75c/0x964 [ 90.468964] (0)[1649:kworker/u8:18][<ffffff82a851fd14>] schedule+0x70/0x90 [ 90.468995] (0)[1649:kworker/u8:18][<ffffff82a79fec00>] __fuse_request_send+0x228/0x3a4 [ 90.469031] (0)[1649:kworker/u8:18][<ffffff82a79feeec>] fuse_simple_request+0x170/0x1c4 [ 90.469068] (0)[1649:kworker/u8:18][<ffffff82a7a070e0>] fuse_file_poll+0x164/0x1c8 [ 90.469107] (0)[1649:kworker/u8:18][<ffffff82a7851050>] do_sys_poll+0x2f4/0x5a0 [ 90.469142] (0)[1649:kworker/u8:18][<ffffff82a78518f4>] do_restart_poll+0x4c/0x90 [ 90.469178] (0)[1649:kworker/u8:18][<ffffff82a76bb32c>] sys_restart_syscall+0x18/0x20 [ 90.469213] (0)[1649:kworker/u8:18][<ffffff82a76835c0>] el0_svc_naked+0x34/0x38 [ 90.469457] (3)[647:dsme-server]Restarting tasks ... Use freezer_do_not_count() to tell freezer to ignore the task while it waits for event. [Sergey: added #include <linux/freezer.h>, cleaned up the patch description] Link: https://bugzilla.kernel.org/show_bug.cgi?id=198879 Fixes: 7d3a07fcb8a0 (fuse: don't mess with blocking signals) Signed-off-by: Ildar Kamaletdinov <i.kamaletdinov@xxxxxx> Signed-off-by: Sergey Shtylyov <s.shtylyov@xxxxxx> --- This patch is against the Linus' repo -- I didn't find a tag suitable for the fixes in Miklos Szeredi's FUSE repo. :-( fs/fuse/dev.c | 3 +++ 1 file changed, 3 insertions(+) Index: linux/fs/fuse/dev.c =================================================================== --- linux.orig/fs/fuse/dev.c +++ linux/fs/fuse/dev.c @@ -8,6 +8,7 @@ #include "fuse_i.h" +#include <linux/freezer.h> #include <linux/init.h> #include <linux/module.h> #include <linux/poll.h> @@ -386,9 +387,11 @@ static void request_wait_answer(struct f } if (!test_bit(FR_FORCE, &req->flags)) { + freezer_do_not_count(); /* Only fatal signals may interrupt this */ err = wait_event_killable(req->waitq, test_bit(FR_FINISHED, &req->flags)); + freezer_count(); if (!err) return;
