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io_uring: fix memory leak when removing provided buffers

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When removing provided buffers, io_buffer structs are not being disposed
of, leading to a memory leak. They can't be freed individually, because
they are allocated in page-sized groups. They need to be added to some
free list instead, such as io_buffers_cache. All callers already hold
the lock protecting it, apart from when destroying buffers, so had to
extend the lock there.

Fixes: cc3cec8367 ("io_uring: speedup provided buffer handling")
Signed-off-by: Wojciech Lukowicz <wlukowicz01@gmail.com>
Link: https://lore.kernel.org/r/20230401195039.404909-2-wlukowicz01@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Wojciech Lukowicz 2023-04-01 20:50:39 +01:00 committed by Jens Axboe
parent c0921e51da
commit b4a72c0589
2 changed files with 5 additions and 2 deletions
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2
io_uring/io_uring.c
View File

@ -2789,8 +2789,8 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
io_eventfd_unregister(ctx);
io_alloc_cache_free(&ctx->apoll_cache, io_apoll_cache_free);
io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);
mutex_unlock(&ctx->uring_lock);
io_destroy_buffers(ctx);
mutex_unlock(&ctx->uring_lock);
if (ctx->sq_creds)
put_cred(ctx->sq_creds);
if (ctx->submitter_task)

5
io_uring/kbuf.c
View File

@ -228,11 +228,14 @@ static int __io_remove_buffers(struct io_ring_ctx *ctx,
return i;
}
/* protects io_buffers_cache */
lockdep_assert_held(&ctx->uring_lock);
while (!list_empty(&bl->buf_list)) {
struct io_buffer *nxt;
nxt = list_first_entry(&bl->buf_list, struct io_buffer, list);
list_del(&nxt->list);
list_move(&nxt->list, &ctx->io_buffers_cache);
if (++i == nbufs)
return i;
cond_resched();