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Wysocki" , Alexander Viro , Christian Brauner , Jan Kara Cc: linux-fsdevel@vger.kernel.org, Pavel Machek , linux-pm@vger.kernel.org, John Stultz , Sadrul Chowdhury , "Rafael J. Wysocki" Content-Type: text/plain; charset="UTF-8" Similar to epoll_wait(), threads sleeping in do_select() and do_poll() sleep in TASK_INTERRUPTIBLE via poll_schedule_timeout(). During system suspend and resume, these threads are woken up by the freezer solely to transition to TASK_FROZEN, and woken again upon thaw only to re-evaluate file descriptors with no pending activity and sleep again. A previous attempt to make select() and poll() freezable in commit 9745cdb36da8 ("select: use freezable blocking call") was reverted in commit 59612d187912 ("Revert "select: use freezable blocking call"") alongside the epoll revert due to issues caused by the legacy freezer architecture. Following the freezer overhaul in commit f5d39b020809 ("freezer,sched: Rewrite core freezer logic"), tasks in TASK_FREEZABLE are safely frozen in-place into TASK_FROZEN without running userspace code or experiencing premature wakeups before resume completes. Pass TASK_FREEZABLE to poll_schedule_timeout() in do_select() and do_poll() (TASK_INTERRUPTIBLE | TASK_FREEZABLE) so that polling threads remain asleep undisturbed across suspend/resume cycles. Reviewed-by: Jan Kara Acked-by: Rafael J. Wysocki Signed-off-by: Sadrul Chowdhury --- v1 -> v2: - Rebased against current mainline (torvalds/linux.git master). - Collected Reviewed-by from Jan Kara and Acked-by from Rafael J. Wysocki. fs/select.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/select.c b/fs/select.c index 95d76531015a..03318d678187 100644 --- a/fs/select.c +++ b/fs/select.c @@ -600,7 +600,7 @@ static noinline_for_stack int do_select(int n, fd_set_bits *fds, struct timespec to = &expire; } - if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE, + if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE | TASK_FREEZABLE, to, slack)) timed_out = 1; } @@ -962,7 +962,7 @@ static int do_poll(struct poll_list *list, struct poll_wqueues *wait, to = &expire; } - if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack)) + if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE | TASK_FREEZABLE, to, slack)) timed_out = 1; } return count; -- 2.56.0.212.g129ede20d9-goog