Re: [PATCH] Debugging: Keep track of page owners

From: Dave Hansen
Date: Fri Dec 07 2012 - 17:58:57 EST


On 12/07/2012 02:44 PM, Andrew Morton wrote:
> AFACIT that difference was undescribed. I can see that the new version
> uses the stack-tracing infrastructure, but the change to
> pagetypeinfo_showmixedcount_print() is a mystery.

Ahhh, I assume you're talking about this hunk:

>> @@ -976,10 +976,7 @@ static void pagetypeinfo_showmixedcount_print(struct seq_file *m,
>>
>> pagetype = allocflags_to_migratetype(page->gfp_mask);
>> if (pagetype != mtype) {
>> - if (is_migrate_cma(pagetype))
>> - count[MIGRATE_MOVABLE]++;
>> - else
>> - count[mtype]++;
>> + count[mtype]++;
>> break;
>> }

That was to fix the comment that Laura Abbott made about it miscounting
MIGRATE_CMA pages.

My patch-sending scripts were choking a bit on the text description in
your patch. I'm using a long-ago-forked copy of your patch-utils and
the DESC/EDESC in the patch I imported is giving them fits when I send
via email and stripping large parts of the description. I'm happy to
resend via email, too, but here, the raw patch (will the full description):

https://www.sr71.net/~dave/linux/pageowner.patch

The important description that the scripts managed to strip out when
emailed was this:

Updated 12/4/2012 - should apply to 3.7 kernels. I did a quick
sniff-test to make sure that this boots and produces some sane
output, but it's not been exhaustively tested.

* Moved file over to debugfs (no reason to keep polluting /proc)
* Now using generic stack tracking infrastructure
* Added check for MIGRATE_CMA pages to explicitly count them
as movable.

The new snprint_stack_trace() probably belongs in its own patch
if this were to get merged, but it won't kill anyone as it stands.

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