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io_uring: fix NULL-mm for linked reqs

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__io_queue_sqe() tries to handle all request of a link,
so it's not enough to grab mm in io_sq_thread_acquire_mm()
based just on the head.

Don't check req->needs_mm and do it always.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
This commit is contained in:
Pavel Begunkov 2020-06-25 12:38:13 +03:00 committed by Jens Axboe
parent f6b6c7d6a9
commit d3cac64c49
1 changed files with 11 additions and 4 deletions
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15
fs/io_uring.c
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@ -1991,10 +1991,9 @@ static void io_sq_thread_drop_mm(struct io_ring_ctx *ctx)
}
}
static int io_sq_thread_acquire_mm(struct io_ring_ctx *ctx,
struct io_kiocb *req)
static int __io_sq_thread_acquire_mm(struct io_ring_ctx *ctx)
{
if (io_op_defs[req->opcode].needs_mm && !current->mm) {
if (!current->mm) {
if (unlikely(!mmget_not_zero(ctx->sqo_mm)))
return -EFAULT;
kthread_use_mm(ctx->sqo_mm);
@ -2003,6 +2002,14 @@ static int io_sq_thread_acquire_mm(struct io_ring_ctx *ctx,
return 0;
}
static int io_sq_thread_acquire_mm(struct io_ring_ctx *ctx,
struct io_kiocb *req)
{
if (!io_op_defs[req->opcode].needs_mm)
return 0;
return __io_sq_thread_acquire_mm(ctx);
}
#ifdef CONFIG_BLOCK
static bool io_resubmit_prep(struct io_kiocb *req, int error)
{
@ -2781,7 +2788,7 @@ static void io_async_buf_retry(struct callback_head *cb)
ctx = req->ctx;
__set_current_state(TASK_RUNNING);
if (!io_sq_thread_acquire_mm(ctx, req)) {
if (!__io_sq_thread_acquire_mm(ctx)) {
mutex_lock(&ctx->uring_lock);
__io_queue_sqe(req, NULL);
mutex_unlock(&ctx->uring_lock);