Re: [RFC:PATCH 00/07] VM File Tails

Luiz Fernando N. Capitulino
2007-08-31T21:00:06Z

Hi Dave,

Em Wed, 29 Aug 2007 16:53:25 -0400
Dave Kleikamp <shaggy@linux.vnet.ibm.com> escreveu:

| This is a rewrite of my "VM File Tails" work. The idea is to store tails
| of files that are smaller than the base page size in kmalloc'ed memory,
| allowing more efficient use of memory. This is especially important when
| the base page size is large, such as 64 KB on powerpc.

I've got the OOPS below while trying this series.

It has happened while halting the machine, but before this one I've
got two hangs and a OOPS, but was unable to get the backtrace because
the serial console wasn't working properly. Now it did.

I've tried to reproduce it many times w/o success.

[ 2618.789047] BUG: unable to handle kernel NULL pointer dereference at virtual address 00000044
[ 2618.891267] printing eip:
[ 2618.923588] c0157120
[ 2618.949679] *pde = 00000000
[ 2618.983052] Oops: 0000 [#1]
[ 2619.016400] SMP
[ 2619.038542] Modules linked in: nfs lockd nfs_acl sunrpc capability commoncap af_packet ipv6 ide_cd ide_core binfmt_misd
[ 2619.546147] CPU: 0
[ 2619.546148] EIP: 0060:[<c0157120>] Not tainted VLI
[ 2619.546149] EFLAGS: 00010286 (2.6.23-rc4-vm1 #5)
[ 2619.694076] EIP is at find_get_page+0x10/0xa0
[ 2619.746151] eax: c0368ee0 ebx: d96c0060 ecx: 00000000 edx: 0000000a
[ 2619.827340] esi: d96c0000 edi: c0368ee0 ebp: d8627e28 esp: d8627e18
[ 2619.908526] ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068
[ 2619.978280] Process udevd (pid: 18087, ti=d8627000 task=d42f3080 task.ti=d8627000)
[ 2620.066743] Stack: 0000000a d96c0060 d96c0000 d96c0018 d8627e30 c016cbef d8627e74 c01721c5
[ 2620.167577] d8627f7c c0178b5f 00008001 c03c70c0 d8627ed0 00000000 d96c0060 c01753b1
[ 2620.268412] d96c0114 0000000a d8627e84 00000000 d96c0060 00000019 00000000 d8627e98
[ 2620.369247] Call Trace:
[ 2620.400641] [<c01053fa>] show_trace_log_lvl+0x1a/0x30
[ 2620.462181] [<c01054bb>] show_stack_log_lvl+0xab/0xd0
[ 2620.523720] [<c01056b1>] show_registers+0x1d1/0x2d0
[ 2620.583183] [<c01058c6>] die+0x116/0x250
[ 2620.631208] [<c011bb6b>] do_page_fault+0x28b/0x6a0
[ 2620.689631] [<c02e80ca>] error_code+0x72/0x78
[ 2620.742854] [<c016cbef>] lookup_swap_cache+0xf/0x30
[ 2620.802316] [<c01721c5>] shmem_getpage+0x225/0x690
[ 2620.860736] [<c017271a>] shmem_fault+0x7a/0xb0
[ 2620.914999] [<c01630d5>] __do_fault+0x55/0x3a0
[ 2620.969265] [<c0165677>] handle_mm_fault+0x107/0x740
[ 2621.029765] [<c011bcfd>] do_page_fault+0x41d/0x6a0
[ 2621.088186] [<c02e80ca>] error_code+0x72/0x78
[ 2621.141411] =======================
[ 2621.184134] Code: c3 0f 0b eb fe 8d b6 00 00 00 00 8b 52 0c eb b8 8d 74 26 00 8d bc 27 00 00 00 00 55 89 e5 57 89 c7 5
[ 2621.416574] EIP: [<c0157120>] find_get_page+0x10/0xa0 SS:ESP 0068:d8627e18
[ 2621.499188] note: udevd[18087] exited with preempt_count 1

--
Luiz Fernando N. Capitulino