kernel/Unused-iocbs-in-a-batch-should-not-be-accounted-as-a.patch

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From 69e4747ee9727d660b88d7e1efe0f4afcb35db1b Mon Sep 17 00:00:00 2001
From: Gleb Natapov <gleb@redhat.com>
Date: Sun, 8 Jan 2012 17:07:28 +0200
Subject: [PATCH] Unused iocbs in a batch should not be accounted as active.
Since commit 080d676de095 ("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>
---
fs/aio.c | 11 +++++++++--
1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 78c514c..969beb0 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -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;
}
--
1.7.7.5