- 01 Aug, 2020 2 commits
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Pavel Begunkov authored
As recently done with with send/recv, flip the if after rw_verify_aread() in io_{read,write}() and tabulise left bits left. This removes mispredicted by a compiler jump on the success/fast path. Signed-off-by:Pavel Begunkov <asml.silence@gmail.com> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
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Pavel Begunkov authored
Use a local var to collect flags in kiocb_set_rw_flags(). That spares some memory writes and allows to replace most of the jumps with MOVEcc. Signed-off-by:
Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by:
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- 31 Jul, 2020 1 commit
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Jens Axboe authored
As soon as we install the file descriptor, we have to assume that it can get arbitrarily closed. We currently account memory (and note that we did) after installing the ring fd, which means that it could be a potential use-after-free condition if the fd is closed right after being installed, but before we fiddle with the ctx. In fact, syzbot reported this exact scenario: BUG: KASAN: use-after-free in io_account_mem fs/io_uring.c:7397 [inline] BUG: KASAN: use-after-free in io_uring_create fs/io_uring.c:8369 [inline] BUG: KASAN: use-after-free in io_uring_setup+0x2797/0x2910 fs/io_uring.c:8400 Read of size 1 at addr ffff888087a41044 by task syz-executor.5/18145 CPU: 0 PID: 18145 Comm: syz-executor.5 Not tainted 5.8.0-rc7-next-20200729-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 io_account_mem fs/io_uring.c:7397 [inline] io_uring_create fs/io_uring.c:8369 [inline] io_uring_setup+0x2797/0x2910 fs/io_uring.c:8400 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45c429 Code: 8d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 5b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f8f121d0c78 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9 RAX: ffffffffffffffda RBX: 0000000000008540 RCX: 000000000045c429 RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000196 RBP: 000000000078bf38 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c R13: 00007fff86698cff R14: 00007f8f121d19c0 R15: 000000000078bf0c Move the accounting of the ring used locked memory before we get and install the ring file descriptor. Cc: stable@vger.kernel.org Reported-by: syzbot+9d46305e76057f30c74e@syzkaller.appspotmail.com Fixes: 30975825 ("io_uring: report pinned memory usage") Reviewed-by:
Stefano Garzarella <sgarzare@redhat.com> Signed-off-by:
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- 30 Jul, 2020 6 commits
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Pavel Begunkov authored
If ->cq_timeouts modifications are done under ->completion_lock, we don't really nee any fetch-and-add and other complex atomics. Replace it with non-atomic FAA, that saves an implicit full memory barrier. Signed-off-by:
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Pavel Begunkov authored
Add a helper to mark ctx->{cq,sq}_check_overflow to get rid of duplicates, and it's clearer to check cq_overflow_list directly anyway. Signed-off-by: -
Pavel Begunkov authored
Always do io_commit_cqring() after completing a request, even if it was accounted as overflowed on the CQ side. Failing to do that may lead to not to pushing deferred requests when needed, and so stalling the whole ring. Signed-off-by:
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Pavel Begunkov authored
All ->cq_overflow modifications should be under completion_lock, otherwise it can report a wrong number to the userspace. Fix it in io_uring_cancel_files(). Signed-off-by:
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Pavel Begunkov authored
Call __io_complete_rw() in io_iopoll_queue() instead of hand coding it. Signed-off-by:
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Pavel Begunkov authored
As io_kiocb have enough space, move ->work out of a union. It's safer this way and removes ->work memcpy bouncing. By the way make tabulation in struct io_kiocb consistent. Signed-off-by:
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- 25 Jul, 2020 3 commits
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Pavel Begunkov authored
Linked requests are hashed, remove a comment stating otherwise. Also move hash bits to emphasise that we don't carry it through loop iteration and set it every time. Signed-off-by:
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Pavel Begunkov authored
Whoever called io_prep_linked_timeout() should also do io_queue_linked_timeout(). __io_queue_sqe() doesn't follow that for the punting path leaving linked timeouts prepared but never queued. Fixes: 6df1db6b ("io_uring: fix mis-refcounting linked timeouts") Signed-off-by:
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Pavel Begunkov authored
Remove REQ_F_WORK_INITIALIZED after io_req_clean_work(). That's a cold path but is safer for those using io_req_clean_work() out of *dismantle_req()/*io_free(). And for the same reason zero work.fs Signed-off-by:
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- 24 Jul, 2020 28 commits
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Pavel Begunkov authored
Move io_req_init_async() into io_grab_files(), it's safer this way. Note that io_queue_async_work() does *init_async(), so it's valid to move out of __io_queue_sqe() punt path. Also, add a helper around io_grab_files(). Signed-off-by:
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Pavel Begunkov authored
Calling into opcode prep handlers may be dangerous, as they re-read SQE but might not re-initialise requests completely. If io_req_defer() passed fast checks and is done with preparations, punt it async. As all other cases are covered with nulling @sqe, this guarantees that io_[opcode]_prep() are visited only once per request. Signed-off-by:
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Xiaoguang Wang authored
In io_sq_thread(), if there are task works to handle, current codes will skip schedule() and go on polling sq again, but forget to clear IORING_SQ_NEED_WAKEUP flag, fix this issue. Also add two helpers to set and clear IORING_SQ_NEED_WAKEUP flag, Signed-off-by:
Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Signed-off-by:
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Pavel Begunkov authored
As every iopoll request have a task ref, it becomes expensive to put them one by one, instead we can put several at once integrating that into io_req_free_batch(). Signed-off-by:
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Pavel Begunkov authored
put_task_struct_many() is as put_task_struct() but puts several references at once. Useful to batching it. Signed-off-by:
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Pavel Begunkov authored
Locked and pinned memory accounting in io_{,un}account_mem() depends on having ->sqo_mm, which is NULL after a recent change for non SQPOLL'ed io_ring. That disables the accounting. Return ->sqo_mm initialisation back, and do __io_sq_thread_acquire_mm() based on IORING_SETUP_SQPOLL flag. Fixes: 8eb06d7e ("io_uring: fix missing ->mm on exit") Signed-off-by: -
Pavel Begunkov authored
io_sqe_buffer_unregister() uses cxt->sqo_mm for memory accounting, but io_ring_ctx_free() drops ->sqo_mm before leaving pinned_vm over-accounted. Postpone mm cleanup for when it's not needed anymore. Fixes: 30975825 ("io_uring: report pinned memory usage") Signed-off-by:
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Pavel Begunkov authored
Don't implement fast path of kbuf freeing and management inlined into io_recv{,msg}(), that's error prone and duplicates handling. Replace it with a helper io_put_recv_kbuf(), which mimics io_put_rw_kbuf() in the io_read/write(). This also keeps cflags calculation in one place, removing duplication between rw and recv/send. Signed-off-by: -
Pavel Begunkov authored
Extract a common helper for cleaning up a selected buffer, this will be used shortly. By the way, correct cflags types to unsigned and, as kbufs are anyway tracked by a flag, remove useless zeroing req->rw.addr. Signed-off-by:
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Pavel Begunkov authored
Move REQ_F_BUFFER_SELECT flag check out of io_recv_buffer_select(), and do that in its call sites That saves us from double error checking and possibly an extra function call. Signed-off-by:
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Pavel Begunkov authored
io_clean_op() may be skipped even if there is a selected io_buffer, that's because *select_buffer() funcions never set REQ_F_NEED_CLEANUP. Trigger io_clean_op() when REQ_F_BUFFER_SELECTED is set as well, and and clear the flag if was freed out of it. Signed-off-by:
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Pavel Begunkov authored
Instead of returning error from io_recv(), go through generic cleanup path, because it'll retain cflags for userspace. Do the same for io_send() for consistency. Signed-off-by:
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Pavel Begunkov authored
With the return on a bad socket, kmsg is always non-null by the end of the function, prune left extra checks and initialisations. Signed-off-by:
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Pavel Begunkov authored
Flip over "if (sock)" condition with return on error, the upper layer will take care. That change will be handy later, but already removes an extra jump from hot path. Signed-off-by:
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Pavel Begunkov authored
Currently, file refs in struct io_submit_state are tracked with 2 vars: @has_refs -- how many refs were initially taken @used_refs -- number of refs used Replace it with a single variable counting how many refs left at the current moment. Signed-off-by:
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Pavel Begunkov authored
RLIMIT_SIZE in needed only for execution from an io-wq context, hence move all preparations from hot path to io-wq work setup. Signed-off-by:
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Pavel Begunkov authored
Every call to io_req_defer_prep() is prepended with allocating ->io, just do that in the function. And while we're at it, mark error paths with unlikey and replace "if (ret < 0)" with "if (ret)". There is only one change in the observable behaviour, that's instead of killing the head request right away on error, it postpones it until the link is assembled, that looks more preferable. Signed-off-by:
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Pavel Begunkov authored
A switch in __io_clean_op() doesn't have default, it's pointless to list opcodes that doesn't do any cleanup. Remove IORING_OP_OPEN* from there. Signed-off-by:
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Pavel Begunkov authored
The only caller of io_req_work_grab_env() is io_prep_async_work(), and they are both initialising req->work. Inline grab_env(), it's easier to keep this way, moreover there already were bugs with misplacing io_req_init_async(). Signed-off-by:
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Pavel Begunkov authored
req->cflags is used only for defer-completion path, just use completion data to store it. With the 4 bytes from the ->sequence patch and compacting io_kiocb, this frees 8 bytes. Signed-off-by:
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Pavel Begunkov authored
req->sequence is used only for deferred (i.e. DRAIN) requests, but initialised for every request. Remove req->sequence from io_kiocb together with its initialisation in io_init_req(). Replace it with a new field in struct io_defer_entry, that will be calculated only when needed in io_req_defer(), which is a slow path. Signed-off-by:
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Pavel Begunkov authored
The only left user of req->list is DRAIN, hence instead of keeping a separate per request list for it, do that with old fashion non-intrusive lists allocated on demand. That's a really slow path, so that's OK. This removes req->list and so sheds 16 bytes from io_kiocb. Signed-off-by:
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Pavel Begunkov authored
poll*() doesn't use req->list, don't init it. Signed-off-by:
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Pavel Begunkov authored
Instead of using shared req->list, hang timeouts up on their own list entry. struct io_timeout have enough extra space for it, but if that will be a problem ->inflight_entry can reused for that. Signed-off-by:
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Pavel Begunkov authored
As with the completion path, also use compl.list for overflowed requests. If cleaned up properly, nobody needs per-op data there anymore. Signed-off-by:
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Pavel Begunkov authored
req->inflight_entry is used to track requests that grabbed files_struct. Let's share it with iopoll list, because the only iopoll'ed ops are reads and writes, which don't need a file table. Signed-off-by:
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Pavel Begunkov authored
It supports both polling and I/O polling. Rename ctx->poll to clearly show that it's only in I/O poll case. Signed-off-by:
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Pavel Begunkov authored
Calling io_req_complete(req) means that the request is done, and there is nothing left but to clean it up. That also means that per-op data after that should not be used, so we're free to reuse it in completion path, e.g. to store overflow_list as done in this patch. Signed-off-by:
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