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

[Dave Jones <davej@redhat.com>]

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@redhat.com> 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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