On Thu, Oct 16, 2008 at 12:25 PM, Dave Anderson <anderson@xxxxxxxxxx> wrote:
>
> ----- "Mike Snitzer" <snitzer@xxxxxxxxx> wrote:
>
>> I'm getting a core when I try to show slab data (kmem -[sS]) on
>> 2.6.25.17 with both a live crash or saved vmcore.
>>
>> The core shows that the segv is coming from memset() via
>> gather_cpudata_list_v2_nodes (memory.c:10119). This is with crash
>> 4.0-7.4, but the same crash occurs with crash 4.0-6.3
>> (memory.c:10108)
>> and older.
>>
>> I've also seen kmem -[sS] segfaults with older kernels too (e.g.
>> 2.6.22.x).
>>
>> Have others experienced this? Would it be useful for me to provide
>> my
>> kernel config?
>
> No that won't help.
Actually I think it may considering kmem -[sS] works perfectly fine on
the same identical 2.6.22.19 kernel if various debug features are
_not_ enabled, see the attached .config diff. Of note:
-# CONFIG_DEBUG_SLAB is not set
+CONFIG_DEBUG_SLAB=y
+CONFIG_DEBUG_SLAB_LEAK=y
Comparable debug features are enabled in my 2.6.25 kernel that causes
crash to segfault.
> It's failing in the BZERO() here:
>
> 10117 for (i = 0; (i < ARRAY_LENGTH(kmem_cache_s_array)) &&
> 10118 (cpudata[i]) && !(index); i++) {
> 10119 BZERO(si->cpudata[i], sizeof(ulong) * vt->kmem_max_limit);
>
> What is "i" equal to when it segfaults? If you have a crash core file,
> print out the contents of the global "vm_table". In that structure
> there is a "kmem_max_cpus" field. If "i" is greater or equal to that,
> then that's one explanation.
i=0 and kmem_max_cpus=4.
thanks,
Mike
--- /boot/config-2.6.22.19-9.ibrix 2008-07-30 06:24:09.000000000 -0400
+++ /boot/config-2.6.22.19-9.ibrix.devel 2008-08-09 07:47:15.000000000 -0400
@@ -1,7 +1,7 @@
#
# Automatically generated make config: don't edit
# Linux kernel version: 2.6.22.19-9.ibrix
-# Mon Jul 28 04:43:08 2008
+# Sat Aug 9 07:34:38 2008
#
CONFIG_X86_64=y
CONFIG_64BIT=y
@@ -40,7 +40,7 @@
#
# General setup
#
-CONFIG_LOCALVERSION=""
+CONFIG_LOCALVERSION=".devel"
# CONFIG_LOCALVERSION_AUTO is not set
CONFIG_SWAP=y
CONFIG_SYSVIPC=y
@@ -2120,7 +2120,7 @@
CONFIG_EXT3_FS_SECURITY=y
# CONFIG_EXT4DEV_FS is not set
CONFIG_JBD=m
-# CONFIG_JBD_DEBUG is not set
+CONFIG_JBD_DEBUG=y
CONFIG_FS_MBCACHE=y
# CONFIG_REISERFS_FS is not set
# CONFIG_JFS_FS is not set
@@ -2334,21 +2334,22 @@
CONFIG_DETECT_SOFTLOCKUP=y
CONFIG_SCHEDSTATS=y
# CONFIG_TIMER_STATS is not set
-# CONFIG_DEBUG_SLAB is not set
+CONFIG_DEBUG_SLAB=y
+CONFIG_DEBUG_SLAB_LEAK=y
# CONFIG_DEBUG_RT_MUTEXES is not set
# CONFIG_RT_MUTEX_TESTER is not set
-# CONFIG_DEBUG_SPINLOCK is not set
+CONFIG_DEBUG_SPINLOCK=y
# CONFIG_DEBUG_MUTEXES is not set
# CONFIG_DEBUG_LOCK_ALLOC is not set
# CONFIG_PROVE_LOCKING is not set
-# CONFIG_DEBUG_SPINLOCK_SLEEP is not set
+CONFIG_DEBUG_SPINLOCK_SLEEP=y
# CONFIG_DEBUG_LOCKING_API_SELFTESTS is not set
# CONFIG_DEBUG_KOBJECT is not set
CONFIG_DEBUG_BUGVERBOSE=y
CONFIG_DEBUG_INFO=y
# CONFIG_DEBUG_VM is not set
CONFIG_DEBUG_LIST=y
-# CONFIG_FRAME_POINTER is not set
+CONFIG_FRAME_POINTER=y
# CONFIG_FORCED_INLINING is not set
# CONFIG_RCU_TORTURE_TEST is not set
# CONFIG_LKDTM is not set
@@ -2356,7 +2357,7 @@
CONFIG_DEBUG_RODATA=y
# CONFIG_IOMMU_DEBUG is not set
CONFIG_DEBUG_STACKOVERFLOW=y
-# CONFIG_DEBUG_STACK_USAGE is not set
+CONFIG_DEBUG_STACK_USAGE=y
#
# Security options
--
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