kernel/git/stable/linux.git/fs/io_uring.c, branch linux-5.8.y

io_uring: Convert advanced XArray uses to the normal API

2020-11-01T11:45:36+00:00

commit 5e2ed8c4f45093698855b1f45cdf43efbf6dd498 upstream. There are no bugs here that I've spotted, it's just easier to use the normal API and there are no performance advantages to using the more verbose advanced API. Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: Fix XArray usage in io_uring_add_task_file

2020-11-01T11:45:36+00:00

commit 236434c3438c4da3dfbd6aeeab807577b85e951a upstream. The xas_store() wasn't paired with an xas_nomem() loop, so if it couldn't allocate memory using GFP_NOWAIT, it would leak the reference to the file descriptor. Also the node pointed to by the xas could be freed between the call to xas_load() under the rcu_read_lock() and the acquisition of the xa_lock. It's easier to just use the normal xa_load/xa_store interface here. Signed-off-by: Matthew Wilcox (Oracle) [axboe: fix missing assign after alloc, cur_uring -> tctx rename] Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: Fix use of XArray in __io_uring_files_cancel

2020-11-01T11:45:36+00:00

commit ce765372bc443573d1d339a2bf4995de385dea3a upstream. We have to drop the lock during each iteration, so there's no advantage to using the advanced API. Convert this to a standard xa_for_each() loop. Reported-by: syzbot+27c12725d8ff0bfe1a13@syzkaller.appspotmail.com Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: no need to call xa_destroy() on empty xarray

2020-11-01T11:45:36+00:00

commit ca6484cd308a671811bf39f3119e81966eb476e3 upstream. The kernel test robot reports this lockdep issue: [child1:659] mbind (274) returned ENOSYS, marking as inactive. [child1:659] mq_timedsend (279) returned ENOSYS, marking as inactive. [main] 10175 iterations. [F:7781 S:2344 HI:2397] [ 24.610601] [ 24.610743] ================================ [ 24.611083] WARNING: inconsistent lock state [ 24.611437] 5.9.0-rc7-00017-g0f2122045b9462 #5 Not tainted [ 24.611861] -------------------------------- [ 24.612193] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. [ 24.612660] ksoftirqd/0/7 [HC0[0]:SC1[3]:HE0:SE0] takes: [ 24.613086] f00ed998 (&xa->xa_lock#4){+.?.}-{2:2}, at: xa_destroy+0x43/0xc1 [ 24.613642] {SOFTIRQ-ON-W} state was registered at: [ 24.614024] lock_acquire+0x20c/0x29b [ 24.614341] _raw_spin_lock+0x21/0x30 [ 24.614636] io_uring_add_task_file+0xe8/0x13a [ 24.614987] io_uring_create+0x535/0x6bd [ 24.615297] io_uring_setup+0x11d/0x136 [ 24.615606] __ia32_sys_io_uring_setup+0xd/0xf [ 24.615977] do_int80_syscall_32+0x53/0x6c [ 24.616306] restore_all_switch_stack+0x0/0xb1 [ 24.616677] irq event stamp: 939881 [ 24.616968] hardirqs last enabled at (939880): [<8105592d>] __local_bh_enable_ip+0x13c/0x145 [ 24.617642] hardirqs last disabled at (939881): [<81b6ace3>] _raw_spin_lock_irqsave+0x1b/0x4e [ 24.618321] softirqs last enabled at (939738): [<81b6c7c8>] __do_softirq+0x3f0/0x45a [ 24.618924] softirqs last disabled at (939743): [<81055741>] run_ksoftirqd+0x35/0x61 [ 24.619521] [ 24.619521] other info that might help us debug this: [ 24.620028] Possible unsafe locking scenario: [ 24.620028] [ 24.620492] CPU0 [ 24.620685] ---- [ 24.620894] lock(&xa->xa_lock#4); [ 24.621168] [ 24.621381] lock(&xa->xa_lock#4); [ 24.621695] [ 24.621695] *** DEADLOCK *** [ 24.621695] [ 24.622154] 1 lock held by ksoftirqd/0/7: [ 24.622468] #0: 823bfb94 (rcu_callback){....}-{0:0}, at: rcu_process_callbacks+0xc0/0x155 [ 24.623106] [ 24.623106] stack backtrace: [ 24.623454] CPU: 0 PID: 7 Comm: ksoftirqd/0 Not tainted 5.9.0-rc7-00017-g0f2122045b9462 #5 [ 24.624090] Call Trace: [ 24.624284] ? show_stack+0x40/0x46 [ 24.624551] dump_stack+0x1b/0x1d [ 24.624809] print_usage_bug+0x17a/0x185 [ 24.625142] mark_lock+0x11d/0x1db [ 24.625474] ? print_shortest_lock_dependencies+0x121/0x121 [ 24.625905] __lock_acquire+0x41e/0x7bf [ 24.626206] lock_acquire+0x20c/0x29b [ 24.626517] ? xa_destroy+0x43/0xc1 [ 24.626810] ? lock_acquire+0x20c/0x29b [ 24.627110] _raw_spin_lock_irqsave+0x3e/0x4e [ 24.627450] ? xa_destroy+0x43/0xc1 [ 24.627725] xa_destroy+0x43/0xc1 [ 24.627989] __io_uring_free+0x57/0x71 [ 24.628286] ? get_pid+0x22/0x22 [ 24.628544] __put_task_struct+0xf2/0x163 [ 24.628865] put_task_struct+0x1f/0x2a [ 24.629161] delayed_put_task_struct+0xe2/0xe9 [ 24.629509] rcu_process_callbacks+0x128/0x155 [ 24.629860] __do_softirq+0x1a3/0x45a [ 24.630151] run_ksoftirqd+0x35/0x61 [ 24.630443] smpboot_thread_fn+0x304/0x31a [ 24.630763] kthread+0x124/0x139 [ 24.631016] ? sort_range+0x18/0x18 [ 24.631290] ? kthread_create_worker_on_cpu+0x17/0x17 [ 24.631682] ret_from_fork+0x1c/0x28 which is complaining about xa_destroy() grabbing the xa lock in an IRQ disabling fashion, whereas the io_uring uses cases aren't interrupt safe. This is really an xarray issue, since it should not assume the lock type. But for our use case, since we know the xarray is empty at this point, there's no need to actually call xa_destroy(). So just get rid of it. Fixes: 0f2122045b94 ("io_uring: don't rely on weak ->files references") Reported-by: kernel test robot Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: reference ->nsproxy for file table commands

2020-11-01T11:45:35+00:00

commit 9b8284921513fc1ea57d87777283a59b05862f03 upstream. If we don't get and assign the namespace for the async work, then certain paths just don't work properly (like /dev/stdin, /proc/mounts, etc). Anything that references the current namespace of the given task should be assigned for async work on behalf of that task. Cc: stable@vger.kernel.org # v5.5+ Reported-by: Al Viro Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: don't rely on weak ->files references

2020-11-01T11:45:35+00:00

commit 0f2122045b946241a9e549c2a76cea54fa58a7ff upstream. Grab actual references to the files_struct. To avoid circular references issues due to this, we add a per-task note that keeps track of what io_uring contexts a task has used. When the tasks execs or exits its assigned files, we cancel requests based on this tracking. With that, we can grab proper references to the files table, and no longer need to rely on stashing away ring_fd and ring_file to check if the ring_fd may have been closed. Cc: stable@vger.kernel.org # v5.5+ Reviewed-by: Pavel Begunkov Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: enable task/files specific overflow flushing

2020-11-01T11:45:35+00:00

commit e6c8aa9ac33bd7c968af7816240fc081401fddcd upstream. This allows us to selectively flush out pending overflows, depending on the task and/or files_struct being passed in. No intended functional changes in this patch. Reviewed-by: Pavel Begunkov Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: return cancelation status from poll/timeout/files handlers

2020-11-01T11:45:35+00:00

commit 76e1b6427fd8246376a97e3227049d49188dfb9c upstream. Return whether we found and canceled requests or not. This is in preparation for using this information, no functional changes in this patch. Reviewed-by: Pavel Begunkov Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: unconditionally grab req->task

2020-11-01T11:45:35+00:00

commit e3bc8e9dad7f2f83cc807111d4472164c9210153 upstream. Sometimes we assign a weak reference to it, sometimes we grab a reference to it. Clean this up and make it unconditional, and drop the flag related to tracking this state. Reviewed-by: Pavel Begunkov Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: stash ctx task reference for SQPOLL

2020-11-01T11:45:35+00:00

commit 2aede0e417db846793c276c7a1bbf7262c8349b0 upstream. We can grab a reference to the task instead of stashing away the task files_struct. This is doable without creating a circular reference between the ring fd and the task itself. Reviewed-by: Pavel Begunkov Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman