| Message ID | 20190108165645.19311-12-axboe@kernel.dk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/16] fs: add an iopoll method to struct file_operations | expand |
> + if (!state) > + req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); Just return an error here if kmem_cache_alloc fails. > + if (req) > + io_req_init(ctx, req); Because all the other ones can't reached this with a NULL req.
On 1/9/19 5:13 AM, Christoph Hellwig wrote: >> + if (!state) >> + req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); > > Just return an error here if kmem_cache_alloc fails. > >> + if (req) >> + io_req_init(ctx, req); > > Because all the other ones can't reached this with a NULL req. This is different in the current tree, since I properly fixed the ctx ref issue.
On Wed, Jan 09, 2019 at 09:57:59AM -0700, Jens Axboe wrote: > On 1/9/19 5:13 AM, Christoph Hellwig wrote: > >> + if (!state) > >> + req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); > > > > Just return an error here if kmem_cache_alloc fails. > > > >> + if (req) > >> + io_req_init(ctx, req); > > > > Because all the other ones can't reached this with a NULL req. > > This is different in the current tree, since I properly fixed the > ctx ref issue. Your tree does a percpu_ref_tryget very first, and then leaks that if kmem_cache_alloc_bulk fails, and also is inconsistent for NULL vs ERR_PTR returns. I think you want something like this on top: diff --git a/fs/io_uring.c b/fs/io_uring.c index 35d055dcbc22..6c95749e9601 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -250,14 +250,6 @@ static struct io_uring_event *io_peek_cqring(struct io_ring_ctx *ctx) return &ring->events[tail & ctx->cq_ring.ring_mask]; } -static bool io_req_init(struct io_ring_ctx *ctx, struct io_kiocb *req) -{ - req->ki_ctx = ctx; - INIT_LIST_HEAD(&req->ki_list); - req->ki_flags = 0; - return true; -} - static void io_ring_drop_ctx_ref(struct io_ring_ctx *ctx, unsigned refs) { percpu_ref_put_many(&ctx->refs, refs); @@ -274,9 +266,11 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx, if (!percpu_ref_tryget(&ctx->refs)) return NULL; - if (!state) + if (!state) { req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); - else if (!state->free_iocbs) { + if (!req) + goto out_drop_ref; + } else if (!state->free_iocbs) { size_t size; int ret; @@ -284,7 +278,7 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx, ret = kmem_cache_alloc_bulk(kiocb_cachep, GFP_KERNEL, size, state->iocbs); if (ret <= 0) - return ERR_PTR(-ENOMEM); + goto out_drop_ref; state->free_iocbs = ret - 1; state->cur_iocb = 1; req = state->iocbs[0]; @@ -294,11 +288,11 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx, state->cur_iocb++; } - if (req) { - io_req_init(ctx, req); - return req; - } + req->ki_ctx = ctx; + req->ki_flags = 0; + return req; +out_drop_ref: io_ring_drop_ctx_ref(ctx, 1); return NULL; }
On 1/9/19 12:03 PM, Christoph Hellwig wrote: > On Wed, Jan 09, 2019 at 09:57:59AM -0700, Jens Axboe wrote: >> On 1/9/19 5:13 AM, Christoph Hellwig wrote: >>>> + if (!state) >>>> + req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); >>> >>> Just return an error here if kmem_cache_alloc fails. >>> >>>> + if (req) >>>> + io_req_init(ctx, req); >>> >>> Because all the other ones can't reached this with a NULL req. >> >> This is different in the current tree, since I properly fixed the >> ctx ref issue. > > Your tree does a percpu_ref_tryget very first, and then leaks that if > kmem_cache_alloc_bulk fails, and also is inconsistent for NULL vs > ERR_PTR returns. I think you want something like this on top: I fixed it up while doing the rebase already. Just haven't pushed anything out until I've had a chance to run it through testing.
diff --git a/fs/io_uring.c b/fs/io_uring.c index 11d045f0f799..62778d7ffb8d 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -135,6 +135,13 @@ struct io_submit_state { struct list_head req_list; unsigned int req_count; + /* + * io_kiocb alloc cache + */ + void *iocbs[IO_IOPOLL_BATCH]; + unsigned int free_iocbs; + unsigned int cur_iocb; + /* * File reference cache */ @@ -210,15 +217,33 @@ static void io_req_init(struct io_ring_ctx *ctx, struct io_kiocb *req) req->ki_flags = 0; } -static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx) +static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx, + struct io_submit_state *state) { struct io_kiocb *req; - req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); - if (!req) - return NULL; + if (!state) + req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); + else if (!state->free_iocbs) { + size_t size; + int ret; + + size = min_t(size_t, state->ios_left, ARRAY_SIZE(state->iocbs)); + ret = kmem_cache_alloc_bulk(kiocb_cachep, GFP_KERNEL, size, + state->iocbs); + if (ret <= 0) + return ERR_PTR(-ENOMEM); + state->free_iocbs = ret - 1; + state->cur_iocb = 1; + req = state->iocbs[0]; + } else { + req = state->iocbs[state->cur_iocb]; + state->free_iocbs--; + state->cur_iocb++; + } - io_req_init(ctx, req); + if (req) + io_req_init(ctx, req); return req; } @@ -773,7 +798,7 @@ static int __io_submit_one(struct io_ring_ctx *ctx, if (unlikely(iocb->flags)) return -EINVAL; - req = io_get_req(ctx); + req = io_get_req(ctx, state); if (unlikely(!req)) return -EAGAIN; @@ -844,6 +869,9 @@ static void io_submit_state_end(struct io_submit_state *state) if (!list_empty(&state->req_list)) io_flush_state_reqs(state->ctx, state); io_file_put(state, NULL); + if (state->free_iocbs) + kmem_cache_free_bulk(kiocb_cachep, state->free_iocbs, + &state->iocbs[state->cur_iocb]); } /* @@ -855,6 +883,7 @@ static void io_submit_state_start(struct io_submit_state *state, state->ctx = ctx; INIT_LIST_HEAD(&state->req_list); state->req_count = 0; + state->free_iocbs = 0; state->file = NULL; state->ios_left = max_ios; #ifdef CONFIG_BLOCK
Similarly to how we use the state->ios_left to know how many references to get to a file, we can use it to allocate the io_kiocb's we need in bulk. Signed-off-by: Jens Axboe <axboe@kernel.dk> --- fs/io_uring.c | 41 +++++++++++++++++++++++++++++++++++------ 1 file changed, 35 insertions(+), 6 deletions(-)