From: Keith Owens <kaos@sgi.com>
To: linux-ia64@vger.kernel.org
Subject: Deadlock in ia64_mca_cmc_int_caller
Date: Sat, 06 Dec 2003 04:16:09 +0000 [thread overview]
Message-ID: <marc-linux-ia64-107068420607204@msgid-missing> (raw)
ia64_mca_cmc_int_caller() calls smp_call_function() which waits until
all cpus have taken the IPI before returning. This interacts badly
with locks that are sometimes taken with interrupts disabled and
sometimes with interrupts enabled, smp_call_function can deadlock.
cpu 3 cpu 0
Holds tasklist_lock with interrupts enabled,
it did read_lock() or write_lock().
Does read_lock_irq() or
write_lock_irq(). Spinning
disabled waiting for tasklist_lock.
CMC interrupt occurs
ia64_mca_cmc_int_caller() calls smp_call_function()
smp_call_function() sends IPI to other cpus
IPI on cpu 0 blocked, it is disabled
waiting for tasklist_lock.
smp_call_function() waits until IPI reaches
all other cpus.
cpu 0 never responds, we never release the
tasklist lock, deadlock.
AFAICT it is never safe to call smp_call_function() from an interrupt
handler.
The unsafe nature of smp_call_function is not ia64 specific. ix86 can
deadlock this way if any ix86 code calls smp_call_function from an
interrupt handler.
next reply other threads:[~2003-12-06 4:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-12-06 4:16 Keith Owens [this message]
2003-12-06 15:23 ` Deadlock in ia64_mca_cmc_int_caller Alex Williamson
2003-12-06 22:50 ` Keith Owens
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