diff options
| author | Jens Axboe <axboe@kernel.dk> | 2020-08-25 07:58:00 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-08-25 12:05:57 -0600 |
| commit | 6b7898eb180df12767933466b7855b23103ad489 (patch) | |
| tree | d706d26c9eeb38cde5a618f000c6d1210c43151a | |
| parent | 842163154b87b01d8f516af15ad8916eb1661016 (diff) | |
| download | linux-visconti-6b7898eb180df12767933466b7855b23103ad489.tar.gz | |
io_uring: fix imbalanced sqo_mm accounting
We do the initial accounting of locked_vm and pinned_vm before we have
setup ctx->sqo_mm, which means we can end up having not accounted the
memory at setup time, but still decrement it when we exit. This causes
an imbalance in the accounting.
Setup ctx->sqo_mm earlier in io_uring_create(), before we do the first
accounting of mm->{locked,pinned}_vm. This also unifies the state
grabbing for the ctx, and eliminates a failure case in
io_sq_offload_start().
Fixes: f74441e6311a ("io_uring: account locked memory before potential error case")
Reported-by: Robert M. Muncrief <rmuncrief@humanavance.com>
Reported-by: Niklas Schnelle <schnelle@linux.ibm.com>
Tested-by: Niklas Schnelle <schnelle@linux.ibm.com>
Tested-by: Robert M. Muncrief <rmuncrief@humanavance.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | fs/io_uring.c | 10 |
1 files changed, 3 insertions, 7 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index e030b33fa53e1..384df86dfc692 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7447,9 +7447,6 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx, { int ret; - mmgrab(current->mm); - ctx->sqo_mm = current->mm; - if (ctx->flags & IORING_SETUP_SQPOLL) { ret = -EPERM; if (!capable(CAP_SYS_ADMIN)) @@ -7494,10 +7491,6 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx, return 0; err: io_finish_async(ctx); - if (ctx->sqo_mm) { - mmdrop(ctx->sqo_mm); - ctx->sqo_mm = NULL; - } return ret; } @@ -8547,6 +8540,9 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p, ctx->user = user; ctx->creds = get_current_cred(); + mmgrab(current->mm); + ctx->sqo_mm = current->mm; + /* * Account memory _before_ installing the file descriptor. Once * the descriptor is installed, it can get closed at any time. Also |