Commit 69e4747e authored Jan 08, 2012 by Gleb Natapov Committed by Linus Torvalds Jan 13, 2012

Unused iocbs in a batch should not be accounted as active.



Since commit 080d676d ("aio: allocate kiocbs in batches") iocbs are
allocated in a batch during processing of first iocbs.  All iocbs in a
batch are automatically added to ctx->active_reqs list and accounted in
ctx->reqs_active.

If one (not the last one) of iocbs submitted by an user fails, further
iocbs are not processed, but they are still present in ctx->active_reqs
and accounted in ctx->reqs_active.  This causes process to stuck in a D
state in wait_for_all_aios() on exit since ctx->reqs_active will never
go down to zero.  Furthermore since kiocb_batch_free() frees iocb
without removing it from active_reqs list the list become corrupted
which may cause oops.

Fix this by removing iocb from ctx->active_reqs and updating
ctx->reqs_active in kiocb_batch_free().

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Cc: stable@kernel.org   # 3.2
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent a3301b75

fs/aio.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -476,14 +476,21 @@ static void kiocb_batch_init(struct kiocb_batch *batch, long total)
		batch->count = total;
		}

		static void kiocb_batch_free(struct kiocb_batch *batch)
		static void kiocb_batch_free(struct kioctx ctx, struct kiocb_batch batch)
		{
		struct kiocb req, n;

		if (list_empty(&batch->head))
		return;

		spin_lock_irq(&ctx->ctx_lock);
		list_for_each_entry_safe(req, n, &batch->head, ki_batch) {
		list_del(&req->ki_batch);
		list_del(&req->ki_list);
		kmem_cache_free(kiocb_cachep, req);
		ctx->reqs_active--;
		}
		spin_unlock_irq(&ctx->ctx_lock);
		}

		/*
		@@ -1742,7 +1749,7 @@ long do_io_submit(aio_context_t ctx_id, long nr,
		}
		blk_finish_plug(&plug);

		kiocb_batch_free(&batch);
		kiocb_batch_free(ctx, &batch);
		put_ioctx(ctx);
		return i ? i : ret;
		}