* [PATCH 2/2] aio: fix kioctx not being freed after cancellation at exit time
@ 2013-02-13 17:46 Benjamin LaHaise
2013-02-14 1:36 ` Kent Overstreet
0 siblings, 1 reply; 2+ messages in thread
From: Benjamin LaHaise @ 2013-02-13 17:46 UTC (permalink / raw)
To: Andrew Morton, Kent Overstreet; +Cc: linux-aio, linux-fsdevel, Linux Kernel
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 adding a wake_up() in batch_complete_aio()
and modifying the wait_event() condition in free_ioctx() appropriately.
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
---
fs/aio.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index dc52b0c..46f9dd0 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) != ctx->nr));
avail = (head <= ctx->shadow_tail ?
ctx->shadow_tail : ctx->nr) - head;
@@ -754,6 +756,7 @@ void batch_complete_aio(struct batch_complete *batch)
* with free_ioctx()
*/
atomic_inc(&req->ki_ctx->reqs_available);
+ wake_up(&req->ki_ctx->wait);
aio_put_req(req);
continue;
}
--
1.7.4.1
--
"Thought is the essence of where you are now."
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH 2/2] aio: fix kioctx not being freed after cancellation at exit time
2013-02-13 17:46 [PATCH 2/2] aio: fix kioctx not being freed after cancellation at exit time Benjamin LaHaise
@ 2013-02-14 1:36 ` Kent Overstreet
0 siblings, 0 replies; 2+ messages in thread
From: Kent Overstreet @ 2013-02-14 1:36 UTC (permalink / raw)
To: Benjamin LaHaise; +Cc: Andrew Morton, linux-aio, linux-fsdevel, Linux Kernel
On Wed, Feb 13, 2013 at 12:46:36PM -0500, Benjamin LaHaise wrote:
> 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 adding a wake_up() in batch_complete_aio()
> and modifying the wait_event() condition in free_ioctx() appropriately.
>
> Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
> ---
> fs/aio.c | 5 ++++-
> 1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/fs/aio.c b/fs/aio.c
> index dc52b0c..46f9dd0 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) != ctx->nr));
That test looks backwards - I think we want to wait until reqs_available
== ctx->nr
>
> avail = (head <= ctx->shadow_tail ?
> ctx->shadow_tail : ctx->nr) - head;
> @@ -754,6 +756,7 @@ void batch_complete_aio(struct batch_complete *batch)
> * with free_ioctx()
> */
> atomic_inc(&req->ki_ctx->reqs_available);
> + wake_up(&req->ki_ctx->wait);
> aio_put_req(req);
> continue;
> }
> --
> 1.7.4.1
>
>
> --
> "Thought is the essence of where you are now."
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