On Thu, Jun 16, 2016 at 02:52:52PM +0800, Hillf Danton wrote: > > > > From: Ebru Akagunduz <ebru.akagunduz@xxxxxxxxx> > > > > Currently khugepaged makes swapin readahead under down_write. This patch > > supplies to make swapin readahead under down_read instead of down_write. > > > > The patch was tested with a test program that allocates 800MB of memory, > > writes to it, and then sleeps. The system was forced to swap out all. > > Afterwards, the test program touches the area by writing, it skips a page > > in each 20 pages of the area. > > > > Link: http://lkml.kernel.org/r/1464335964-6510-4-git-send-email-ebru.akagunduz@xxxxxxxxx > > Signed-off-by: Ebru Akagunduz <ebru.akagunduz@xxxxxxxxx> > > Cc: Hugh Dickins <hughd@xxxxxxxxxx> > > Cc: Rik van Riel <riel@xxxxxxxxxx> > > Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> > > Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> > > Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> > > Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > > Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx> > > Cc: Mel Gorman <mgorman@xxxxxxx> > > Cc: David Rientjes <rientjes@xxxxxxxxxx> > > Cc: Vlastimil Babka <vbabka@xxxxxxx> > > Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> > > Cc: Michal Hocko <mhocko@xxxxxxx> > > Cc: Minchan Kim <minchan.kim@xxxxxxxxx> > > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > --- > > mm/huge_memory.c | 92 ++++++++++++++++++++++++++++++++++++++------------------ > > 1 file changed, 63 insertions(+), 29 deletions(-) > > > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > > index f2bc57c45d2f..96dfe3f09bf6 100644 > > --- a/mm/huge_memory.c > > +++ b/mm/huge_memory.c > > @@ -2378,6 +2378,35 @@ static bool hugepage_vma_check(struct vm_area_struct *vma) > > } > > > > /* > > + * If mmap_sem temporarily dropped, revalidate vma > > + * before taking mmap_sem. > > See below > > @@ -2401,11 +2430,18 @@ static void __collapse_huge_page_swapin(struct mm_struct *mm, > > continue; > > swapped_in++; > > ret = do_swap_page(mm, vma, _address, pte, pmd, > > - FAULT_FLAG_ALLOW_RETRY|FAULT_FLAG_RETRY_NOWAIT, > > + FAULT_FLAG_ALLOW_RETRY, > > Add a description in change log for it please. Ebru, would you address it? > > pteval); > > + /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */ > > + if (ret & VM_FAULT_RETRY) { > > + down_read(&mm->mmap_sem); > > + /* vma is no longer available, don't continue to swapin */ > > + if (hugepage_vma_revalidate(mm, vma, address)) > > + return false; > > Revalidate vma _after_ acquiring mmap_sem, but the above comment says _before_. Ditto. > > + if (!__collapse_huge_page_swapin(mm, vma, address, pmd)) { > > + up_read(&mm->mmap_sem); > > + goto out; > > Jump out with mmap_sem released, > > > + result = hugepage_vma_revalidate(mm, vma, address); > > + if (result) > > + goto out; > > but jump out again with mmap_sem held. > > They are cleaned up in subsequent darns? I didn't fold fixups for these > -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>