This v2 patch replaces both "aio: fix kioctx not being freed after
cancellation at exit time" and "aio: only suppress events from cancelled
kiocbs if free_ioctx() is in progress". Kent's feedback is indeed correct.
The recent changes overhauling fs/aio.c introduced a bug that results in the
kioctx not being freed when outstanding kiocbs are cancelled at exit_aio()
time. Specifically, a kiocb that is cancelled has its completion events
discarded by batch_complete_aio(), which then fails to wake up the process
stuck in free_ioctx(). Fix this by removing the event suppression in
batch_complete_aio() and modify the wait_event() condition in free_ioctx()
appropriately.
This patch was tested with the cancel operation in the thread based code
posted yesterday.
Signed-off-by: Benjamin LaHaise <bcrl@xxxxxxxxx>
---
fs/aio.c | 15 +++------------
1 files changed, 3 insertions(+), 12 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index dc52b0c..6ea766c 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -335,7 +335,9 @@ static void free_ioctx(struct kioctx *ctx)
kunmap_atomic(ring);
while (atomic_read(&ctx->reqs_available) < ctx->nr) {
- wait_event(ctx->wait, head != ctx->shadow_tail);
+ wait_event(ctx->wait,
+ (head != ctx->shadow_tail) ||
+ (atomic_read(&ctx->reqs_available) >= ctr->nr));
avail = (head <= ctx->shadow_tail ?
ctx->shadow_tail : ctx->nr) - head;
@@ -747,17 +749,6 @@ void batch_complete_aio(struct batch_complete *batch)
n = rb_parent(n);
}
- if (unlikely(xchg(&req->ki_cancel,
- KIOCB_CANCELLED) == KIOCB_CANCELLED)) {
- /*
- * Can't use the percpu reqs_available here - could race
- * with free_ioctx()
- */
- atomic_inc(&req->ki_ctx->reqs_available);
- aio_put_req(req);
- continue;
- }
-
if (unlikely(req->ki_eventfd != eventfd)) {
if (eventfd) {
/* Make event visible */
--
1.7.4.1
--
"Thought is the essence of where you are now."
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