The patch titled
genirq core: fix handle_level_irq()
has been added to the -mm tree. Its filename is
genirq-core-fix-handle_level_irq.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: genirq core: fix handle_level_irq()
From: Ingo Molnar <mingo@xxxxxxx>
While porting the -rt tree to 2.6.18-rc7 i noticed the following
screaming-IRQ scenario on an SMP system:
2274 0Dn.:1 0.001ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf)
2274 0Dn.:1 0.010ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf)
2274 0Dn.:1 0.020ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf)
2274 0Dn.:1 0.029ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf)
2274 0Dn.:1 0.039ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf)
2274 0Dn.:1 0.048ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf)
2274 0Dn.:1 0.058ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf)
2274 0Dn.:1 0.068ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf)
2274 0Dn.:1 0.077ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf)
2274 0Dn.:1 0.087ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf)
2274 0Dn.:1 0.097ms: do_IRQ+0xc/0x103 <= (ret_from_intr+0x0/0xf)
As it turns out, the bug is caused by handle_level_irq(), which if it races
with another CPU already handling this IRQ, it _unmasks_ the IRQ line on
the way out. This is not how 2.6.17 works, and we introduced this bug in
one of the early genirq cleanups right before it went into -mm. (the bug
was not in the genirq patchset for a long time, and we didnt notice the bug
due to the lack of -rt rebase to the new genirq code. -rt, and
hardirq-preemption in particular opens up such races much wider than
anything else.)
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Kyle McMartin <kyle@xxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxx>
Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/irq/chip.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff -puN kernel/irq/chip.c~genirq-core-fix-handle_level_irq kernel/irq/chip.c
--- a/kernel/irq/chip.c~genirq-core-fix-handle_level_irq
+++ a/kernel/irq/chip.c
@@ -252,7 +252,7 @@ handle_level_irq(unsigned int irq, struc
mask_ack_irq(desc, irq);
if (unlikely(desc->status & IRQ_INPROGRESS))
- goto out;
+ goto out_unlock;
desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
kstat_cpu(cpu).irqs[irq]++;
@@ -263,7 +263,7 @@ handle_level_irq(unsigned int irq, struc
action = desc->action;
if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
desc->status |= IRQ_PENDING;
- goto out;
+ goto out_unlock;
}
desc->status |= IRQ_INPROGRESS;
@@ -276,9 +276,9 @@ handle_level_irq(unsigned int irq, struc
spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
-out:
if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
desc->chip->unmask(irq);
+out_unlock:
spin_unlock(&desc->lock);
}
_
Patches currently in -mm which might be from mingo@xxxxxxx are
origin.patch
genirq-core-fix-handle_level_irq.patch
fix-longstanding-load-balancing-bug-in-the-scheduler.patch
git-netdev-all.patch
x86-remaining-pda-patches.patch
bootmem-use-max_dma_address-instead-of-low32limit.patch
slab-fix-lockdep-warnings.patch
slab-fix-lockdep-warnings-fix.patch
slab-fix-lockdep-warnings-fix-2.patch
frv-improve-frvs-use-of-generic-irq-handling.patch
frv-permit-__do_irq-to-be-dispensed-with.patch
i386-kill-references-to-xtime.patch
make-touch_nmi_watchdog-imply-touch_softlockup_watchdog-on.patch
make-touch_nmi_watchdog-imply-touch_softlockup_watchdog-on-fix.patch
let-warn_on-warn_on_once-return-the-condition.patch
let-warn_on-warn_on_once-return-the-condition-fix.patch
let-warn_on-warn_on_once-return-the-condition-fix-2.patch
spinlock_debug-dont-recompute-jiffies_per_loop.patch
lockdep-dont-pull-in-includes-when-lockdep-disabled.patch
rtmutex-clean-up-and-remove-some-extra-spinlocks.patch
rtmutex-clean-up-and-remove-some-extra-spinlocks-more.patch
lockdep-print-kernel-version.patch
check-return-value-of-cpu_callback.patch
posix-timers-fix-clock_nanosleep-doesnt-return-the-remaining-time-in-compatibility-mode-2.patch
posix-timers-fix-the-flags-handling-in-posix_cpu_nsleep-2.patch
has_stopped_jobs-cleanup.patch
__dequeue_signal-cleanup.patch
simplify-update_times-avoid-jiffies-jiffies_64-aliasing-problem-2.patch
do_sched_setscheduler-dont-take-tasklist_lock.patch
introduce-is_rt_policy-helper.patch
sched_setscheduler-fix-policy-checks.patch
reparent_to_init-use-has_rt_policy.patch
futex_find_get_task-dont-take-tasklist_lock.patch
sys_get_robust_list-dont-take-tasklist_lock.patch
make-spinlock-rwlock-annotations-more-accurate-by-using.patch
replace-_spin_trylock-with-spin_trylock-in-the-irq.patch
lockdep-core-add-enable-disable_irq_irqsave-irqrestore-apis.patch
set-exit_dead-state-in-do_exit-not-in-schedule.patch
kill-pf_dead-flag.patch
introduce-task_dead-state.patch
select_bad_process-kill-a-bogus-pf_dead-task_dead-check.patch
maximum-latency-tracking-infrastructure.patch
maximum-latency-tracking-infrastructure-tidy.patch
lockdep-core-improve-the-lock-chain-hash.patch
remove-the-old-bd_mutex-lockdep-annotation.patch
new-bd_mutex-lockdep-annotation.patch
ntp-move-all-the-ntp-related-code-to-ntpc.patch
nfsd-lockdep-annotation.patch
sched-force-sbin-init-off-isolated-cpus.patch
sched-remove-unnecessary-sched-group-allocations.patch
sched-remove-unnecessary-sched-group-allocations-fix.patch
lower-migration-thread-stop-machine-prio.patch
sched-generic-sched_group-cpu-power-setup.patch
sched-fixing-wrong-comment-for-find_idlest_cpu.patch
scheduler-numa-aware-placement-of-sched_group_allnodes.patch
sched-add-above-background-load-function.patch
mm-implement-swap-prefetching.patch
sched-cleanup-remove-task_t-convert-to-struct-task_struct-prefetch.patch
genirq-msi-restore-__do_irq-compat-logic-temporarily.patch
genirq-convert-the-x86_64-architecture-to-irq-chips.patch
genirq-convert-the-i386-architecture-to-irq-chips.patch
genirq-irq-convert-the-move_irq-flag-from-a-32bit-word-to-a-single-bit.patch
genirq-irq-add-moved_masked_irq.patch
genirq-x86_64-irq-reenable-migrating-irqs-to-other-cpus.patch
genirq-msi-simplify-msi-enable-and-disable.patch
genirq-msi-make-the-msi-boolean-tests-return-either-0-or-1.patch
genirq-msi-implement-helper-functions-read_msi_msg-and-write_msi_msg.patch
genirq-msi-refactor-the-msi_ops.patch
genirq-msi-simplify-the-msi-irq-limit-policy.patch
genirq-irq-add-a-dynamic-irq-creation-api.patch
genirq-ia64-irq-dynamic-irq-support.patch
genirq-i386-irq-dynamic-irq-support.patch
genirq-x86_64-irq-dynamic-irq-support.patch
genirq-msi-make-the-msi-code-irq-based-and-not-vector-based.patch
genirq-x86_64-irq-move-msi-message-composition-into-io_apicc.patch
genirq-i386-irq-move-msi-message-composition-into-io_apicc.patch
genirq-msi-only-build-msi-apicc-on-ia64.patch
genirq-x86_64-irq-remove-the-msi-assumption-that-irq-==-vector.patch
genirq-i386-irq-remove-the-msi-assumption-that-irq-==-vector.patch
genirq-irq-remove-msi-hacks.patch
genirq-irq-generalize-the-check-for-hardirq_bits.patch
genirq-x86_64-irq-make-the-external-irq-handlers-report-their-vector-not-the-irq-number.patch
genirq-x86_64-irq-make-vector_irq-per-cpu.patch
genirq-x86_64-irq-make-vector_irq-per-cpu-warning-fix.patch
genirq-x86_64-irq-kill-gsi_irq_sharing.patch
genirq-x86_64-irq-kill-irq-compression.patch
detect-atomic-counter-underflows.patch
debug-shared-irqs.patch
make-frame_pointer-default=y.patch
mutex-subsystem-synchro-test-module.patch
vdso-print-fatal-signals.patch
vdso-improve-print_fatal_signals-support-by-adding-memory-maps.patch
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