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| author | Pavel Begunkov <asml.silence@gmail.com> | 2020-11-05 14:06:19 +0000 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-11-05 09:15:24 -0700 |
| commit | ef9865a442286e2737f37f56eb54c12ef8465905 (patch) | |
| tree | 453e5741e011199802f722057090d626b0807741 | |
| parent | 99b328084f6a98bcee9fcd423c82ccfd52115da5 (diff) | |
| download | linux-ef9865a442286e2737f37f56eb54c12ef8465905.tar.gz linux-ef9865a442286e2737f37f56eb54c12ef8465905.tar.bz2 linux-ef9865a442286e2737f37f56eb54c12ef8465905.zip | |
io_uring: don't forget to task-cancel drained reqs
If there is a long-standing request of one task locking up execution of
deferred requests, and the defer list contains requests of another task
(all files-less), then a potential execution of __io_uring_task_cancel()
by that another task will sleep until that first long-standing request
completion, and that may take long.
E.g.
tsk1: req1/read(empty_pipe) -> tsk2: req(DRAIN)
Then __io_uring_task_cancel(tsk2) waits for req1 completion.
It seems we even can manufacture a complicated case with many tasks
sharing many rings that can lock them forever.
Cancel deferred requests for __io_uring_task_cancel() as well.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | fs/io_uring.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index d6f7f8b3837f..3d489cf31926 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -8496,6 +8496,7 @@ static void io_attempt_cancel(struct io_ring_ctx *ctx, struct io_kiocb *req) } static void io_cancel_defer_files(struct io_ring_ctx *ctx, + struct task_struct *task, struct files_struct *files) { struct io_defer_entry *de = NULL; @@ -8503,7 +8504,8 @@ static void io_cancel_defer_files(struct io_ring_ctx *ctx, spin_lock_irq(&ctx->completion_lock); list_for_each_entry_reverse(de, &ctx->defer_list, list) { - if (io_match_files(de->req, files)) { + if (io_task_match(de->req, task) && + io_match_files(de->req, files)) { list_cut_position(&list, &ctx->defer_list, &de->list); break; } @@ -8529,7 +8531,6 @@ static bool io_uring_cancel_files(struct io_ring_ctx *ctx, if (list_empty_careful(&ctx->inflight_list)) return false; - io_cancel_defer_files(ctx, files); /* cancel all at once, should be faster than doing it one by one*/ io_wq_cancel_cb(ctx->io_wq, io_wq_files_match, files, true); @@ -8621,6 +8622,11 @@ static void io_uring_cancel_task_requests(struct io_ring_ctx *ctx, io_sq_thread_park(ctx->sq_data); } + if (files) + io_cancel_defer_files(ctx, NULL, files); + else + io_cancel_defer_files(ctx, task, NULL); + io_cqring_overflow_flush(ctx, true, task, files); while (__io_uring_cancel_task_requests(ctx, task, files)) { |