Re: WARNING: at mm/page-writeback.c:1990__set_page_dirty_nobuffers+0x13a/0x170()

From: Dave Jones
Date: Sun Jun 03 2012 - 18:13:39 EST


On Sun, Jun 03, 2012 at 02:59:22PM -0700, Linus Torvalds wrote:
> On Sun, Jun 3, 2012 at 1:53 PM, Dave Jones <davej@xxxxxxxxxx> wrote:
> >
> > running just over two hours with that commit reverted with no obvious ill effects so far.
>
> And how quickly have you usually seen the problems? Would you have
> considered two ours "good" in your bisection thing?

Yeah, usually see something go awry in an hour or less.

> Also, just to check: Hugh sent out a patch called "mm: fix warning in
> __set_page_dirty_nobuffers". Is that applied in your tree too, or did
> the __set_page_dirty_nobuffers() warning go away with just the revert?

That is applied. Otherwise I see the warning he refers to.

> I'm just trying to figure out exactly what you are testing. When you
> said "test with that (and Hugh's last patch) backed out", the "and
> Hugh's last patch" part was a bit ambiguous. Do you mean the trial
> patch in this thread (backed out) or do you mean "*with* Hugh's patch
> for the __set_page_dirty_nobuffers() warning".

The former. (This).

--- 3.4.0+/mm/compaction.c 2012-05-30 08:17:19.396008280 -0700
+++ linux/mm/compaction.c 2012-06-01 20:59:56.840204915 -0700
@@ -369,6 +369,8 @@ static bool rescue_unmovable_pageblock(s
{
unsigned long pfn, start_pfn, end_pfn;
struct page *start_page, *end_page;
+ struct zone *zone;
+ unsigned long flags;

pfn = page_to_pfn(page);
start_pfn = pfn & ~(pageblock_nr_pages - 1);
@@ -378,7 +380,8 @@ static bool rescue_unmovable_pageblock(s
end_page = pfn_to_page(end_pfn);

/* Do not deal with pageblocks that overlap zones */
- if (page_zone(start_page) != page_zone(end_page))
+ zone = page_zone(start_page);
+ if (zone != page_zone(end_page))
return false;

for (page = start_page, pfn = start_pfn; page < end_page; pfn++,
@@ -399,8 +402,10 @@ static bool rescue_unmovable_pageblock(s
return false;
}

+ spin_lock_irqsave(&zone->lock, flags);
set_pageblock_migratetype(page, MIGRATE_MOVABLE);
- move_freepages_block(page_zone(page), page, MIGRATE_MOVABLE);
+ move_freepages_block(zone, page, MIGRATE_MOVABLE);
+ spin_unlock_irqrestore(&zone->lock, flags);
return true;



I do see something else weird going on, but it seems like an unrelated problem.
I have a lot of processes hanging after calling sys_renameat.

I'll dig some more on that, and post a follow-up.

Dave


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