projects / pve-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| 25aba572 FE |
1 | From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
| 2 | From: Jens Axboe <axboe@kernel.dk> | |
| 3 | Date: Tue, 31 Aug 2021 13:53:00 -0600 | |
| 4 | Subject: [PATCH] io-wq: fix queue stalling race | |
| 5 | ||
| 6 | We need to set the stalled bit early, before we drop the lock for adding | |
| 7 | us to the stall hash queue. If not, then we can race with new work being | |
| 8 | queued between adding us to the stall hash and io_worker_handle_work() | |
| 9 | marking us stalled. | |
| 10 | ||
| 11 | Signed-off-by: Jens Axboe <axboe@kernel.dk> | |
| 12 | [backport] | |
| 13 | Signed-off-by: Fabian Ebner <f.ebner@proxmox.com> | |
| 14 | --- | |
| 15 | fs/io-wq.c | 15 +++++++-------- | |
| 16 | 1 file changed, 7 insertions(+), 8 deletions(-) | |
| 17 | ||
| 18 | diff --git a/fs/io-wq.c b/fs/io-wq.c | |
| 19 | index 6612d0aa497e..33678185f3bc 100644 | |
| 20 | --- a/fs/io-wq.c | |
| 21 | +++ b/fs/io-wq.c | |
| 22 | @@ -437,8 +437,7 @@ static bool io_worker_can_run_work(struct io_worker *worker, | |
| 23 | } | |
| 24 | ||
| 25 | static struct io_wq_work *io_get_next_work(struct io_wqe *wqe, | |
| 26 | - struct io_worker *worker, | |
| 27 | - bool *stalled) | |
| 28 | + struct io_worker *worker) | |
| 29 | __must_hold(wqe->lock) | |
| 30 | { | |
| 31 | struct io_wq_work_node *node, *prev; | |
| 32 | @@ -476,10 +475,14 @@ static struct io_wq_work *io_get_next_work(struct io_wqe *wqe, | |
| 33 | } | |
| 34 | ||
| 35 | if (stall_hash != -1U) { | |
| 36 | + /* | |
| 37 | + * Set this before dropping the lock to avoid racing with new | |
| 38 | + * work being added and clearing the stalled bit. | |
| 39 | + */ | |
| 40 | + wqe->flags |= IO_WQE_FLAG_STALLED; | |
| 41 | raw_spin_unlock(&wqe->lock); | |
| 42 | io_wait_on_hash(wqe, stall_hash); | |
| 43 | raw_spin_lock(&wqe->lock); | |
| 44 | - *stalled = true; | |
| 45 | } | |
| 46 | ||
| 47 | return NULL; | |
| 48 | @@ -519,7 +522,6 @@ static void io_worker_handle_work(struct io_worker *worker) | |
| 49 | ||
| 50 | do { | |
| 51 | struct io_wq_work *work; | |
| 52 | - bool stalled; | |
| 53 | get_next: | |
| 54 | /* | |
| 55 | * If we got some work, mark us as busy. If we didn't, but | |
| 56 | @@ -528,12 +530,9 @@ static void io_worker_handle_work(struct io_worker *worker) | |
| 57 | * can't make progress, any work completion or insertion will | |
| 58 | * clear the stalled flag. | |
| 59 | */ | |
| 60 | - stalled = false; | |
| 61 | - work = io_get_next_work(wqe, worker, &stalled); | |
| 62 | + work = io_get_next_work(wqe, worker); | |
| 63 | if (work) | |
| 64 | __io_worker_busy(wqe, worker, work); | |
| 65 | - else if (stalled) | |
| 66 | - wqe->flags |= IO_WQE_FLAG_STALLED; | |
| 67 | ||
| 68 | raw_spin_unlock_irq(&wqe->lock); | |
| 69 | if (!work) | |
| 70 | -- | |
| 71 | 2.30.2 | |
| 72 |