On Wed, Jun 29, 2022 at 08:17:57AM +1000, Dave Chinner wrote:
> On Tue, Jun 28, 2022 at 02:18:24PM +0100, Matthew Wilcox wrote:
> > On Tue, Jun 28, 2022 at 12:31:55PM +0100, Matthew Wilcox wrote:
> > > On Tue, Jun 28, 2022 at 12:27:40PM +0100, Matthew Wilcox wrote:
> > > > On Tue, Jun 28, 2022 at 05:31:20PM +1000, Dave Chinner wrote:
> > > > > So using this technique, I've discovered that there's a dirty page
> > > > > accounting leak that eventually results in fsx hanging in
> > > > > balance_dirty_pages().
> > > >
> > > > Alas, I think this is only an accounting error, and not related to
> > > > the problem(s) that Darrick & Zorro are seeing. I think what you're
> > > > seeing is dirty pages being dropped at truncation without the
> > > > appropriate accounting. ie this should be the fix:
> > >
> > > Argh, try one that actually compiles.
> >
> > ... that one's going to underflow the accounting. Maybe I shouldn't
> > be writing code at 6am?
> >
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index f7248002dad9..4eec6ee83e44 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -18,6 +18,7 @@
> > #include <linux/shrinker.h>
> > #include <linux/mm_inline.h>
> > #include <linux/swapops.h>
> > +#include <linux/backing-dev.h>
> > #include <linux/dax.h>
> > #include <linux/khugepaged.h>
> > #include <linux/freezer.h>
> > @@ -2439,11 +2440,15 @@ static void __split_huge_page(struct page *page, struct list_head *list,
> > __split_huge_page_tail(head, i, lruvec, list);
> > /* Some pages can be beyond EOF: drop them from page cache */
> > if (head[i].index >= end) {
> > - ClearPageDirty(head + i);
> > - __delete_from_page_cache(head + i, NULL);
> > + struct folio *tail = page_folio(head + i);
> > +
> > if (shmem_mapping(head->mapping))
> > shmem_uncharge(head->mapping->host, 1);
> > - put_page(head + i);
> > + else if (folio_test_clear_dirty(tail))
> > + folio_account_cleaned(tail,
> > + inode_to_wb(folio->mapping->host));
> > + __filemap_remove_folio(tail, NULL);
> > + folio_put(tail);
> > } else if (!PageAnon(page)) {
> > __xa_store(&head->mapping->i_pages, head[i].index,
> > head + i, 0);
> >
>
> Yup, that fixes the leak.
>
> Tested-by: Dave Chinner <dchinner@xxxxxxxxxx>
Four hours of generic/522 running is long enough to conclude that this
is likely the fix for my problem and migrate long soak testing to my
main g/522 rig and:
Tested-by: Darrick J. Wong <djwong@xxxxxxxxxx>
--D
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david@xxxxxxxxxxxxx
