Messages in this thread | | | Subject | Re: Kernel 4.1.6 Panic due to slab corruption | From | Nikolay Borisov <> | Date | Wed, 9 Sep 2015 14:40:32 +0300 |
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On 09/08/2015 06:15 PM, Christoph Lameter wrote: > On Tue, 8 Sep 2015, Nikolay Borisov wrote: > >>> You have read https://www.kernel.org/doc/Documentation/vm/slub.txt? >> >> I've read that I'm also following the merge/nomerge thread on the DM >> mailing list. I guess my understanding is wrong in that if multiple slab >> caches are merged, then it's enough to just instrument the cache to >> which they are being merge in order to have them all instrumented? I >> guess that's not the case, so even though slab caches might be merge >> they are still somehow considered different entities in the kernel? > > Enabling debugging on bootup disables merging. > > If you switch debug options later then its possible to affect all aliases > caches. But then these option changes are only allowed to be used in such > a way as to not affect the object layout. You can switch on sanity checks > and double free checks I believe but nothing else.
I tried the following:
[root@kernighan vm]# ./slabinfo -da kmalloc-32 Cannot write to dma-kmalloc-32/sanity [root@kernighan vm]# ./slabinfo -dF kmalloc-32 Cannot write to dma-kmalloc-32/sanity [root@kernighan vm]# ./slabinfo -dz kmalloc-32 kmalloc-32 not empty cannot enable redzoning [root@kernighan vm]# ./slabinfo -dp kmalloc-32 kmalloc-32 not empty cannot enable poisoning [root@kernighan vm]# ./slabinfo -du kmalloc-32 kmalloc-32 not empty cannot enable tracking [root@kernighan vm]# ./slabinfo -dt ^kmalloc-32$ kmalloc-32 can only enable trace for one slab at a time
I did however had success with enabling tracing but couldn't see where the output is produced - tried dmesg and the ftrace buffer but nothing turned up.
But it seems it is not possible to enable any debugging whatsoever, so I will restor to doing it at boot time. In this case can you advice which options might not result in very high performance degradation - I'm thinking of sanity checking and maybe redzoning?
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