kernel/linux.git, branch v5.8.2

Linux 5.8.2

2020-08-19T06:27:10+00:00

Tested-by: Shuah Khan Signed-off-by: Greg Kroah-Hartman

task_work: only grab task signal lock when needed

2020-08-19T06:27:10+00:00

commit ebf0d100df0731901c16632f78d78d35f4123bc4 upstream. If JOBCTL_TASK_WORK is already set on the targeted task, then we need not go through {lock,unlock}_task_sighand() to set it again and queue a signal wakeup. This is safe as we're checking it _after_ adding the new task_work with cmpxchg(). The ordering is as follows: task_work_add() get_signal() -------------------------------------------------------------- STORE(task->task_works, new_work); STORE(task->jobctl); mb(); mb(); LOAD(task->jobctl); LOAD(task->task_works); This speeds up TWA_SIGNAL handling quite a bit, which is important now that io_uring is relying on it for all task_work deliveries. Cc: Peter Zijlstra Cc: Jann Horn Acked-by: Oleg Nesterov Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: enable lookup of links holding inflight files

2020-08-19T06:27:10+00:00

commit f254ac04c8744cf7bfed012717eac34eacc65dfb upstream. When a process exits, we cancel whatever requests it has pending that are referencing the file table. However, if a link is holding a reference, then we cannot find it by simply looking at the inflight list. Enable checking of the poll and timeout list to find the link, and cancel it appropriately. Cc: stable@vger.kernel.org Reported-by: Josef Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: add missing REQ_F_COMP_LOCKED for nested requests

2020-08-19T06:27:10+00:00

commit 9b7adba9eaec28e0e4343c96d0dbeb9578802f5f upstream. When we traverse into failing links or timeouts, we need to ensure we propagate the REQ_F_COMP_LOCKED flag to ensure that we correctly signal to the completion side that we already hold the completion lock. Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: hold 'ctx' reference around task_work queue + execute

2020-08-19T06:27:09+00:00

commit 6d816e088c359866f9867057e04f244c608c42fe upstream. We're holding the request reference, but we need to go one higher to ensure that the ctx remains valid after the request has finished. If the ring is closed with pending task_work inflight, and the given io_kiocb finishes sync during issue, then we need a reference to the ring itself around the task_work execution cycle. Cc: stable@vger.kernel.org # v5.7+ Reported-by: syzbot+9b260fc33297966f5a8e@syzkaller.appspotmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: Fix NULL pointer dereference in loop_rw_iter()

2020-08-19T06:27:09+00:00

commit 2dd2111d0d383df104b144e0d1f6b5a00cb7cd88 upstream. loop_rw_iter() does not check whether the file has a read or write function. This can lead to NULL pointer dereference when the user passes in a file descriptor that does not have read or write function. The crash log looks like this: [ 99.834071] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 99.835364] #PF: supervisor instruction fetch in kernel mode [ 99.836522] #PF: error_code(0x0010) - not-present page [ 99.837771] PGD 8000000079d62067 P4D 8000000079d62067 PUD 79d8c067 PMD 0 [ 99.839649] Oops: 0010 [#2] SMP PTI [ 99.840591] CPU: 1 PID: 333 Comm: io_wqe_worker-0 Tainted: G D 5.8.0 #2 [ 99.842622] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014 [ 99.845140] RIP: 0010:0x0 [ 99.845840] Code: Bad RIP value. [ 99.846672] RSP: 0018:ffffa1c7c01ebc08 EFLAGS: 00010202 [ 99.848018] RAX: 0000000000000000 RBX: ffff92363bd67300 RCX: ffff92363d461208 [ 99.849854] RDX: 0000000000000010 RSI: 00007ffdbf696bb0 RDI: ffff92363bd67300 [ 99.851743] RBP: ffffa1c7c01ebc40 R08: 0000000000000000 R09: 0000000000000000 [ 99.853394] R10: ffffffff9ec692a0 R11: 0000000000000000 R12: 0000000000000010 [ 99.855148] R13: 0000000000000000 R14: ffff92363d461208 R15: ffffa1c7c01ebc68 [ 99.856914] FS: 0000000000000000(0000) GS:ffff92363dd00000(0000) knlGS:0000000000000000 [ 99.858651] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 99.860032] CR2: ffffffffffffffd6 CR3: 000000007ac66000 CR4: 00000000000006e0 [ 99.861979] Call Trace: [ 99.862617] loop_rw_iter.part.0+0xad/0x110 [ 99.863838] io_write+0x2ae/0x380 [ 99.864644] ? kvm_sched_clock_read+0x11/0x20 [ 99.865595] ? sched_clock+0x9/0x10 [ 99.866453] ? sched_clock_cpu+0x11/0xb0 [ 99.867326] ? newidle_balance+0x1d4/0x3c0 [ 99.868283] io_issue_sqe+0xd8f/0x1340 [ 99.869216] ? __switch_to+0x7f/0x450 [ 99.870280] ? __switch_to_asm+0x42/0x70 [ 99.871254] ? __switch_to_asm+0x36/0x70 [ 99.872133] ? lock_timer_base+0x72/0xa0 [ 99.873155] ? switch_mm_irqs_off+0x1bf/0x420 [ 99.874152] io_wq_submit_work+0x64/0x180 [ 99.875192] ? kthread_use_mm+0x71/0x100 [ 99.876132] io_worker_handle_work+0x267/0x440 [ 99.877233] io_wqe_worker+0x297/0x350 [ 99.878145] kthread+0x112/0x150 [ 99.878849] ? __io_worker_unuse+0x100/0x100 [ 99.879935] ? kthread_park+0x90/0x90 [ 99.880874] ret_from_fork+0x22/0x30 [ 99.881679] Modules linked in: [ 99.882493] CR2: 0000000000000000 [ 99.883324] ---[ end trace 4453745f4673190b ]--- [ 99.884289] RIP: 0010:0x0 [ 99.884837] Code: Bad RIP value. [ 99.885492] RSP: 0018:ffffa1c7c01ebc08 EFLAGS: 00010202 [ 99.886851] RAX: 0000000000000000 RBX: ffff92363acd7f00 RCX: ffff92363d461608 [ 99.888561] RDX: 0000000000000010 RSI: 00007ffe040d9e10 RDI: ffff92363acd7f00 [ 99.890203] RBP: ffffa1c7c01ebc40 R08: 0000000000000000 R09: 0000000000000000 [ 99.891907] R10: ffffffff9ec692a0 R11: 0000000000000000 R12: 0000000000000010 [ 99.894106] R13: 0000000000000000 R14: ffff92363d461608 R15: ffffa1c7c01ebc68 [ 99.896079] FS: 0000000000000000(0000) GS:ffff92363dd00000(0000) knlGS:0000000000000000 [ 99.898017] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 99.899197] CR2: ffffffffffffffd6 CR3: 000000007ac66000 CR4: 00000000000006e0 Fixes: 32960613b7c3 ("io_uring: correctly handle non ->{read,write}_iter() file_operations") Cc: stable@vger.kernel.org Signed-off-by: Guoyu Huang Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

s390/gmap: improve THP splitting

2020-08-19T06:27:09+00:00

commit ba925fa35057a062ac98c3e8138b013ce4ce351c upstream. During s390_enable_sie(), we need to take care of splitting all qemu user process THP mappings. This is currently done with follow_page(FOLL_SPLIT), by simply iterating over all vma ranges, with PAGE_SIZE increment. This logic is sub-optimal and can result in a lot of unnecessary overhead, especially when using qemu and ASAN with large shadow map. Ilya reported significant system slow-down with one CPU busy for a long time and overall unresponsiveness. Fix this by using walk_page_vma() and directly calling split_huge_pmd() only for present pmds, which greatly reduces overhead. Cc: # v5.4+ Reported-by: Ilya Leoshkevich Tested-by: Ilya Leoshkevich Acked-by: Christian Borntraeger Signed-off-by: Gerald Schaefer Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman

s390/numa: set node distance to LOCAL_DISTANCE

2020-08-19T06:27:09+00:00

commit 535e4fc623fab2e09a0653fc3a3e17f382ad0251 upstream. The node distance is hardcoded to 0, which causes a trouble for some user-level applications. In particular, "libnuma" expects the distance of a node to itself as LOCAL_DISTANCE. This update removes the offending node distance override. Cc: # 4.4 Fixes: 3a368f742da1 ("s390/numa: add core infrastructure") Signed-off-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman

s390/dasd: fix inability to use DASD with DIAG driver

2020-08-19T06:27:09+00:00

commit 9f4aa52387c68049403b59939df5c0dd8e3872cc upstream. During initialization of the DASD DIAG driver a request is issued that has a bio structure that resides on the stack. With virtually mapped kernel stacks this bio address might be in virtual storage which is unsuitable for usage with the diag250 call. In this case the device can not be set online using the DIAG discipline and fails with -EOPNOTSUP. In the system journal the following error message is presented: dasd: X.X.XXXX Setting the DASD online with discipline DIAG failed with rc=-95 Fix by allocating the bio structure instead of having it on the stack. Fixes: ce3dc447493f ("s390: add support for virtually mapped kernel stacks") Signed-off-by: Stefan Haberland Reviewed-by: Peter Oberparleiter Cc: stable@vger.kernel.org #4.20 Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

drm/xen-front: Fix misused IS_ERR_OR_NULL checks

2020-08-19T06:27:09+00:00

commit 14dee058610446aa464254fc5c8e88c7535195e0 upstream. The patch c575b7eeb89f: "drm/xen-front: Add support for Xen PV display frontend" from Apr 3, 2018, leads to the following static checker warning: drivers/gpu/drm/xen/xen_drm_front_gem.c:140 xen_drm_front_gem_create() warn: passing zero to 'ERR_CAST' drivers/gpu/drm/xen/xen_drm_front_gem.c 133 struct drm_gem_object *xen_drm_front_gem_create(struct drm_device *dev, 134 size_t size) 135 { 136 struct xen_gem_object *xen_obj; 137 138 xen_obj = gem_create(dev, size); 139 if (IS_ERR_OR_NULL(xen_obj)) 140 return ERR_CAST(xen_obj); Fix this and the rest of misused places with IS_ERR_OR_NULL in the driver. Fixes: c575b7eeb89f: "drm/xen-front: Add support for Xen PV display frontend" Signed-off-by: Oleksandr Andrushchenko Reported-by: Dan Carpenter Reviewed-by: Dan Carpenter Cc: Link: https://lore.kernel.org/r/20200813062113.11030-3-andr2000@gmail.com Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman