Messages in this thread |  | | From | Song Liu <> | Subject | Re: [PATCH v2] mm,thp: recheck each page before collapsing file THP | Date | Fri, 18 Oct 2019 17:27:12 +0000 |
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> On Oct 18, 2019, at 9:58 AM, Johannes Weiner <hannes@cmpxchg.org> wrote: > > On Fri, Oct 18, 2019 at 12:49:46PM -0400, Johannes Weiner wrote: >> On Fri, Oct 18, 2019 at 09:37:54AM -0700, Song Liu wrote: >>> In collapse_file(), after locking the page, it is necessary to recheck >>> that the page is up-to-date. Add PageUptodate() check for both shmem THP >>> and file THP. >>> >>> Current khugepaged should not try to collapse dirty file THP, because it >>> is limited to read only text. Add a PageDirty check and warning for file >>> THP. This is added after page_mapping() check, because if the page is >>> truncated, it might be dirty. >>> >>> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") >>> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> >>> Cc: Johannes Weiner <hannes@cmpxchg.org> >>> Cc: Hugh Dickins <hughd@google.com> >>> Cc: William Kucharski <william.kucharski@oracle.com> >>> Cc: Andrew Morton <akpm@linux-foundation.org> >>> Signed-off-by: Song Liu <songliubraving@fb.com> >> >> Acked-by: Johannes Weiner <hannes@cmpxchg.org> > > We should also be able to remove the unlocked tests for those two > conditions, right?
Yeah, I think we can remove them.
Thanks, Song
> > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 0a1b4b484ac5..a3ef6ce86bfa 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1601,17 +1601,6 @@ static void collapse_file(struct mm_struct *mm, > result = SCAN_FAIL; > goto xa_unlocked; > } > - } else if (!PageUptodate(page)) { > - xas_unlock_irq(&xas); > - wait_on_page_locked(page); > - if (!trylock_page(page)) { > - result = SCAN_PAGE_LOCK; > - goto xa_unlocked; > - } > - get_page(page); > - } else if (PageDirty(page)) { > - result = SCAN_FAIL; > - goto xa_locked; > } else if (trylock_page(page)) { > get_page(page); > xas_unlock_irq(&xas);
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