Date: Fri, 24 Feb 2006 07:43:21 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-sparc64@freebsd.org Cc: sparc64@freebsd.org, Kris Kennaway <kris@obsecurity.org> Subject: Re: "sched_lock held too long" panic + trace Message-ID: <200602240743.22979.jhb@freebsd.org> In-Reply-To: <20060223230734.GA93088@xor.obsecurity.org> References: <20060223204716.GA90985@xor.obsecurity.org> <20060223230734.GA93088@xor.obsecurity.org>
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On Thursday 23 February 2006 06:07 pm, Kris Kennaway wrote: > On Thu, Feb 23, 2006 at 03:47:16PM -0500, Kris Kennaway wrote: > > One of my e4500s has started panicking regularly under load because > > sched_lock was held for > 5 seconds. Since on sparc64 it always > > deadlocks after this panic instead of entering DDB, I wasn't able to > > track down the cause. Instead, I changed the panic to first > > DELAY(1000000*PCPU_GET(cpuid)) (so that different CPUs don't overlap > > the printfs) and then kdb_backtrace(). > > > > Doing so I obtained the following trace (still a bit corrupted, but > > hopefully more useful). > > > > KDB: stack backtrace: > > hardclock_cpu() at hardclock_cpu+0x6c > > tick_hardclock() at tick_hardclock+0xc4 > > -- interrupt level=3D0xe pil=3D0 %o7=3D0xc0190a98 -- > > _mtx_lock_spin() at _mtx_lock_spin+0xf4 > > tlb_page_demap() at tlb_page_demap+0xa0 > > pmap_zero_page_idle() at pmap_zero_page_idle+0xdc > > vm_page_zero_idle() at vm_page_zero_idle+0x108 > > vm_pagezero() at vm_pagezero+0x4c > > fork_exit() at fork_exit+0x94 > > fork_trampoline() at fork_trampoline+0x8 > > Witness seems to have caught this: > > panic: blockable sleep lock (sleep mutex) system map @ vm/vm_map.c:2995 > db> wh > Tracing pid 1267 tid 100248 td 0xfffff800612a0540 > panic() at panic+0x164 > witness_checkorder() at witness_checkorder+0xc8 > _mtx_lock_flags() at _mtx_lock_flags+0x80 > _vm_map_lock_read() at _vm_map_lock_read+0x3c > vm_map_lookup() at vm_map_lookup+0x1c > vm_fault() at vm_fault+0x68 > trap_pfault() at trap_pfault+0x1a8 > trap() at trap+0x2b0 > -- fast data access mmu miss tar=3D0xe819c000 %o7=3D0xc031d204 -- > cpu_ipi_selected() at cpu_ipi_selected+0x2c > tlb_page_demap() at tlb_page_demap+0x74 > pmap_copy_page() at pmap_copy_page+0x39c > vm_fault() at vm_fault+0xe5c > trap_pfault() at trap_pfault+0x134 > trap() at trap+0xa0 > -- data access protection tar=3D0x4065c524 sfar=3D0x4065d314 sfsr=3D0x800= 005 > %o7=3D0x40350c94 -- This is just a bug. You shouldn't get a pagefault in cpu_ipi_selected(). =2D-=20 John Baldwin <jhb@FreeBSD.org> =A0<>< =A0http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" =A0=3D =A0http://www.FreeBSD.org
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