Hi Ajay,
Could you please provide info on kernel .config settings via commands:
grep HAVE_ALIGNED_STRUCT_PAGE .config
grep CONFIG_HAVE_CMPXCHG_DOUBLE .config
You can try to further debug your problem by defining SLUB_DEBUG_CMPXCHG
manually in mm/slub.c to get some verbose output on the cmpxchg failures.
Is the "Marvell Armada dual core ARMV7" a 32-bit CPU?
--Jesper
On Tue, 29 Mar 2016 15:32:26 -0700 Ajay Patel <patela@xxxxxxxxx> wrote:
> We have custom board with Marvell Armada dual core ARMV7.
> The driver uses buffers from kmalloc-8192 slab heavily.
> When slub_debug is enabled, the kmalloc-8192 active slabs are
> increasing. The slub stats shows cmpxchg_double_fail and objects_partial
> are increasing too. Eventually system panics on oom.
>
> Following patch fixes the issue.
> Has anybody encountered this issue?
> Is this right fix?
>
> I am not in mailing list please cc me.
>
> Thanks
> Ajay
>
>
> --- slub.c.orig Tue Mar 29 11:54:42 2016
> +++ slub.c Tue Mar 29 15:08:30 2016
> @@ -1562,9 +1562,12 @@
> void *freelist;
> unsigned long counters;
> struct page new;
> + int retry_count = 0;
> +#define RETRY_COUNT 10
>
> lockdep_assert_held(&n->list_lock);
>
> +again:
> /*
> * Zap the freelist and set the frozen bit.
> * The old freelist is the list of objects for the
> @@ -1587,8 +1590,13 @@
> if (!__cmpxchg_double_slab(s, page,
> freelist, counters,
> new.freelist, new.counters,
> - "acquire_slab"))
> + "acquire_slab")) {
> + if (retry_count++ < RETRY_COUNT) {
> + new.frozen = 0;
> + goto again;
> + }
> return NULL;
> + }
>
> remove_partial(n, page);
> WARN_ON(!freelist);
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer
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