[Bug 194525] Restart Apache Causes page fault and kernel dump

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=194525

Walter Hop <walter at lifeforms.nl> changed:

           What    |Removed                     |Added
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                 CC|                            |walter at lifeforms.nl

--- Comment #1 from Walter Hop <walter at lifeforms.nl> ---
We currently experience the same problem on FreeBSD 10.1-RELEASE-p1 amd64.

On some Apache restarts, a panic follows. It happens a few times a week since
10.1, but we are not seeing it on all servers, and it tends to happen during
office hours, so it may be related to a certain use of WSGI.

Initially it seemed that disabling softupdates helped, since back-to-back
panics seemingly stabilized the situation, but after 5 days a panic happened
again.

The problem was not present in FreeBSD 9.2 or 10.0.

apache24-2.4.10_2              Version 2.4.x of Apache web server
ap24-mod_wsgi3-3.5             Python WSGI adapter module for Apache

The panic backtrace is the same in all cases.

When finding the kernel function according to
https://www.freebsd.org/doc/faq/advanced.html#idp60797648 it turns up as:
ffffffff8090d9c0 T lf_advlockasync

Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address      = 0x30058
fault code         = supervisor write data, page not present
instruction pointer        = 0x20:0xffffffff8090e46a
stack pointer              = 0x28:0xfffffe000024d780
frame pointer              = 0x28:0xfffffe000024d850
code segment               = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags   = interrupt enabled, resume, IOPL = 0
current process            = 27466 (httpd)
trap number                = 12
panic: page fault
cpuid = 0
KDB: stack backtrace:
#0 0xffffffff80963000 at kdb_backtrace+0x60
#1 0xffffffff80928125 at panic+0x155
#2 0xffffffff80d24f1f at trap_fatal+0x38f
#3 0xffffffff80d25238 at trap_pfault+0x308
#4 0xffffffff80d2489a at trap+0x47a
#5 0xffffffff80d0a782 at calltrap+0x8
#6 0xffffffff8090ec35 at lf_advlock+0x45
#7 0xffffffff809b8e69 at vop_stdadvlock+0xa9
#8 0xffffffff80e44247 at VOP_ADVLOCK_APV+0xa7
#9 0xffffffff808e4919 at kern_fcntl+0xb39
#10 0xffffffff808e3d5c at kern_fcntl_freebsd+0xac
#11 0xffffffff80d25851 at amd64_syscall+0x351
#12 0xffffffff80d0aa6b at Xfast_syscall+0xfb

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