Date: Sun, 28 Apr 2002 09:36:12 -0400 (EDT) From: Robert Watson <rwatson@FreeBSD.org> To: current@FreeBSD.org Cc: dillon@FreeBSD.org Subject: Page fault in swp_pager_meta_build() Message-ID: <Pine.NEB.3.96L.1020428093215.64976I-100000@fledge.watson.org>
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(Matt gets CC'd because he's just unlucky :-)
This system is (as always) a pxeboot'd nfsroot'd dual processor box. This
time, however, it's running straight GENERIC from the main tree instead of
the MAC branch. The box network boots, does a buildkernel -j 8, and then
reboots. It currently has no configured swap, suggesting that things
broke down when it tried to think about using some swap. Not sure how
many loops it took to get to this, but I've seen a couple of different
panics that I'll be posting about as they recur. I'm actually trying to
track an odd mbuf/nfs interaction...
Fatal trap 12: page fault while in kernel mode
cpuid = 0; lapic.id = 00000000
fault virtual address = 0x20097479
fault code = supervisor read, page not present
instruction pointer = 0x8:0xc0337da8
stack pointer = 0x10:0xc8f22b2c
frame pointer = 0x10:0xc8f22b38
code segment = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, def32 1, gran 1
processor eflags = interrupt enabled, resume, IOPL = 0
current process = 2 (pagedaemon)
kernel: type 12 trap, code=0
Stopped at swp_pager_meta_build+0xf0: cmpl %ebx,0x4(%eax)
db> trace
swp_pager_meta_build(c97ff120,0,80000000) at swp_pager_meta_build+0xf0
swap_pager_putpages(c97ff120,c8f22c34,4,0,c8f22bbc) at
swap_pager_putpages+0x57
default_pager_putpages(c97ff120,c8f22c34,4,0,c8f22bbc,c0428be0,1,c03ebb80,8e)
at default_pager_putpages+0x17
vm_pageout_flush(c8f22c34,4,0,c03d0c7a,246) at vm_pageout_flush+0xe5
vm_pageout_clean(c0a09204) at vm_pageout_clean+0x1ec
vm_pageout_scan(0,c034469c,c8f22d34,c023d838,0) at vm_pageout_scan+0x35a
vm_pageout(0,c8f22d48,c8e2c728,c034469c,0) at vm_pageout+0x231
fork_exit(c034469c,0,c8f22d48) at fork_exit+0x88
fork_trampoline() at fork_trampoline+0x37
(kgdb) l *swp_pager_meta_build+0xf0
0xc0337da8 is in swp_pager_meta_build (../../../vm/swap_pager.c:1654).
1649 struct swblock *swap;
1650
1651 index &= ~SWAP_META_MASK;
1652 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask];
1653 while ((swap = *pswap) != NULL) {
1654 if (swap->swb_object == object &&
1655 swap->swb_index == index
1656 ) {
1657 break;
1658 }
Robert N M Watson FreeBSD Core Team, TrustedBSD Project
robert@fledge.watson.org NAI Labs, Safeport Network Services
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