Revision d8550860d910c6b7b70f830f59003b33daaa52c9 authored by Paul Burton on 03 March 2017, 23:26:05 UTC, committed by Ralf Baechle on 30 June 2017, 02:40:18 UTC
When the scheduler sets TIF_NEED_RESCHED & we call into the scheduler from arch/mips/kernel/entry.S we disable interrupts. This is true regardless of whether we reach work_resched from syscall_exit_work, resume_userspace or by looping after calling schedule(). Although we disable interrupts in these paths we don't call trace_hardirqs_off() before calling into C code which may acquire locks, and we therefore leave lockdep with an inconsistent view of whether interrupts are disabled or not when CONFIG_PROVE_LOCKING & CONFIG_DEBUG_LOCKDEP are both enabled. Without tracing this interrupt state lockdep will print warnings such as the following once a task returns from a syscall via syscall_exit_partial with TIF_NEED_RESCHED set: [ 49.927678] ------------[ cut here ]------------ [ 49.934445] WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:3687 check_flags.part.41+0x1dc/0x1e8 [ 49.946031] DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) [ 49.946355] CPU: 0 PID: 1 Comm: init Not tainted 4.10.0-00439-gc9fd5d362289-dirty #197 [ 49.963505] Stack : 0000000000000000 ffffffff81bb5d6a 0000000000000006 ffffffff801ce9c4 [ 49.974431] 0000000000000000 0000000000000000 0000000000000000 000000000000004a [ 49.985300] ffffffff80b7e487 ffffffff80a24498 a8000000ff160000 ffffffff80ede8b8 [ 49.996194] 0000000000000001 0000000000000000 0000000000000000 0000000077c8030c [ 50.007063] 000000007fd8a510 ffffffff801cd45c 0000000000000000 a8000000ff127c88 [ 50.017945] 0000000000000000 ffffffff801cf928 0000000000000001 ffffffff80a24498 [ 50.028827] 0000000000000000 0000000000000001 0000000000000000 0000000000000000 [ 50.039688] 0000000000000000 a8000000ff127bd0 0000000000000000 ffffffff805509bc [ 50.050575] 00000000140084e0 0000000000000000 0000000000000000 0000000000040a00 [ 50.061448] 0000000000000000 ffffffff8010e1b0 0000000000000000 ffffffff805509bc [ 50.072327] ... [ 50.076087] Call Trace: [ 50.079869] [<ffffffff8010e1b0>] show_stack+0x80/0xa8 [ 50.086577] [<ffffffff805509bc>] dump_stack+0x10c/0x190 [ 50.093498] [<ffffffff8015dde0>] __warn+0xf0/0x108 [ 50.099889] [<ffffffff8015de34>] warn_slowpath_fmt+0x3c/0x48 [ 50.107241] [<ffffffff801c15b4>] check_flags.part.41+0x1dc/0x1e8 [ 50.114961] [<ffffffff801c239c>] lock_is_held_type+0x8c/0xb0 [ 50.122291] [<ffffffff809461b8>] __schedule+0x8c0/0x10f8 [ 50.129221] [<ffffffff80946a60>] schedule+0x30/0x98 [ 50.135659] [<ffffffff80106278>] work_resched+0x8/0x34 [ 50.142397] ---[ end trace 0cb4f6ef5b99fe21 ]--- [ 50.148405] possible reason: unannotated irqs-off. [ 50.154600] irq event stamp: 400463 [ 50.159566] hardirqs last enabled at (400463): [<ffffffff8094edc8>] _raw_spin_unlock_irqrestore+0x40/0xa8 [ 50.171981] hardirqs last disabled at (400462): [<ffffffff8094eb98>] _raw_spin_lock_irqsave+0x30/0xb0 [ 50.183897] softirqs last enabled at (400450): [<ffffffff8016580c>] __do_softirq+0x4ac/0x6a8 [ 50.195015] softirqs last disabled at (400425): [<ffffffff80165e78>] irq_exit+0x110/0x128 Fix this by using the TRACE_IRQS_OFF macro to call trace_hardirqs_off() when CONFIG_TRACE_IRQFLAGS is enabled. This is done before invoking schedule() following the work_resched label because: 1) Interrupts are disabled regardless of the path we take to reach work_resched() & schedule(). 2) Performing the tracing here avoids the need to do it in paths which disable interrupts but don't call out to C code before hitting a path which uses the RESTORE_SOME macro that will call trace_hardirqs_on() or trace_hardirqs_off() as appropriate. We call trace_hardirqs_on() using the TRACE_IRQS_ON macro before calling syscall_trace_leave() for similar reasons, ensuring that lockdep has a consistent view of state after we re-enable interrupts. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: linux-mips@linux-mips.org Cc: stable <stable@vger.kernel.org> Patchwork: https://patchwork.linux-mips.org/patch/15385/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Kconfig | -rw-r--r-- | 6.1 KB |
Kconfig.iosched | -rw-r--r-- | 2.7 KB |
Makefile | -rw-r--r-- | 1.4 KB |
badblocks.c | -rw-r--r-- | 14.5 KB |
bfq-cgroup.c | -rw-r--r-- | 33.0 KB |
bfq-iosched.c | -rw-r--r-- | 162.0 KB |
bfq-iosched.h | -rw-r--r-- | 30.6 KB |
bfq-wf2q.c | -rw-r--r-- | 48.9 KB |
bio-integrity.c | -rw-r--r-- | 14.3 KB |
bio.c | -rw-r--r-- | 50.5 KB |
blk-cgroup.c | -rw-r--r-- | 37.6 KB |
blk-core.c | -rw-r--r-- | 92.0 KB |
blk-exec.c | -rw-r--r-- | 2.9 KB |
blk-flush.c | -rw-r--r-- | 16.5 KB |
blk-integrity.c | -rw-r--r-- | 12.1 KB |
blk-ioc.c | -rw-r--r-- | 10.9 KB |
blk-lib.c | -rw-r--r-- | 9.4 KB |
blk-map.c | -rw-r--r-- | 5.9 KB |
blk-merge.c | -rw-r--r-- | 20.0 KB |
blk-mq-cpumap.c | -rw-r--r-- | 2.3 KB |
blk-mq-debugfs.c | -rw-r--r-- | 20.9 KB |
blk-mq-debugfs.h | -rw-r--r-- | 2.1 KB |
blk-mq-pci.c | -rw-r--r-- | 1.5 KB |
blk-mq-sched.c | -rw-r--r-- | 14.8 KB |
blk-mq-sched.h | -rw-r--r-- | 3.4 KB |
blk-mq-sysfs.c | -rw-r--r-- | 8.2 KB |
blk-mq-tag.c | -rw-r--r-- | 11.1 KB |
blk-mq-tag.h | -rw-r--r-- | 2.3 KB |
blk-mq-virtio.c | -rw-r--r-- | 1.7 KB |
blk-mq.c | -rw-r--r-- | 70.6 KB |
blk-mq.h | -rw-r--r-- | 4.4 KB |
blk-settings.c | -rw-r--r-- | 28.8 KB |
blk-softirq.c | -rw-r--r-- | 4.3 KB |
blk-stat.c | -rw-r--r-- | 5.5 KB |
blk-stat.h | -rw-r--r-- | 5.5 KB |
blk-sysfs.c | -rw-r--r-- | 23.3 KB |
blk-tag.c | -rw-r--r-- | 10.0 KB |
blk-throttle.c | -rw-r--r-- | 67.5 KB |
blk-timeout.c | -rw-r--r-- | 5.9 KB |
blk-wbt.c | -rw-r--r-- | 17.6 KB |
blk-wbt.h | -rw-r--r-- | 4.0 KB |
blk-zoned.c | -rw-r--r-- | 7.6 KB |
blk.h | -rw-r--r-- | 10.3 KB |
bounce.c | -rw-r--r-- | 5.8 KB |
bsg-lib.c | -rw-r--r-- | 6.7 KB |
bsg.c | -rw-r--r-- | 22.9 KB |
cfq-iosched.c | -rw-r--r-- | 127.5 KB |
cmdline-parser.c | -rw-r--r-- | 4.9 KB |
compat_ioctl.c | -rw-r--r-- | 20.7 KB |
deadline-iosched.c | -rw-r--r-- | 11.2 KB |
elevator.c | -rw-r--r-- | 26.6 KB |
genhd.c | -rw-r--r-- | 45.6 KB |
ioctl.c | -rw-r--r-- | 15.0 KB |
ioprio.c | -rw-r--r-- | 5.0 KB |
kyber-iosched.c | -rw-r--r-- | 21.0 KB |
mq-deadline.c | -rw-r--r-- | 16.8 KB |
noop-iosched.c | -rw-r--r-- | 2.6 KB |
opal_proto.h | -rw-r--r-- | 9.3 KB |
partition-generic.c | -rw-r--r-- | 16.3 KB |
scsi_ioctl.c | -rw-r--r-- | 19.8 KB |
sed-opal.c | -rw-r--r-- | 57.7 KB |
t10-pi.c | -rw-r--r-- | 4.9 KB |
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