| Message ID | 20190624022336.12465-1-ying.huang@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [-mm] mm, swap: Fix THP swap out | expand |
Hi Huang Ying, On Mon, Jun 24, 2019 at 10:23:36AM +0800, Huang, Ying wrote: > From: Huang Ying <ying.huang@intel.com> > > 0-Day test system reported some OOM regressions for several > THP (Transparent Huge Page) swap test cases. These regressions are > bisected to 6861428921b5 ("block: always define BIO_MAX_PAGES as > 256"). In the commit, BIO_MAX_PAGES is set to 256 even when THP swap > is enabled. So the bio_alloc(gfp_flags, 512) in get_swap_bio() may > fail when swapping out THP. That causes the OOM. > > As in the patch description of 6861428921b5 ("block: always define > BIO_MAX_PAGES as 256"), THP swap should use multi-page bvec to write > THP to swap space. So the issue is fixed via doing that in > get_swap_bio(). > > BTW: I remember I have checked the THP swap code when > 6861428921b5 ("block: always define BIO_MAX_PAGES as 256") was merged, > and thought the THP swap code needn't to be changed. But apparently, > I was wrong. I should have done this at that time. > > Fixes: 6861428921b5 ("block: always define BIO_MAX_PAGES as 256") > Signed-off-by: "Huang, Ying" <ying.huang@intel.com> > Cc: Ming Lei <ming.lei@redhat.com> > Cc: Michal Hocko <mhocko@kernel.org> > Cc: Johannes Weiner <hannes@cmpxchg.org> > Cc: Hugh Dickins <hughd@google.com> > Cc: Minchan Kim <minchan@kernel.org> > Cc: Rik van Riel <riel@redhat.com> > Cc: Daniel Jordan <daniel.m.jordan@oracle.com> > --- > mm/page_io.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/mm/page_io.c b/mm/page_io.c > index 2e8019d0e048..4ab997f84061 100644 > --- a/mm/page_io.c > +++ b/mm/page_io.c > @@ -29,10 +29,9 @@ > static struct bio *get_swap_bio(gfp_t gfp_flags, > struct page *page, bio_end_io_t end_io) > { > - int i, nr = hpage_nr_pages(page); > struct bio *bio; > > - bio = bio_alloc(gfp_flags, nr); > + bio = bio_alloc(gfp_flags, 1); > if (bio) { > struct block_device *bdev; > > @@ -41,9 +40,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags, > bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9; > bio->bi_end_io = end_io; > > - for (i = 0; i < nr; i++) > - bio_add_page(bio, page + i, PAGE_SIZE, 0); bio_add_page() supposes to work, just wondering why it doesn't recently. Could you share me one test case for reproducing it? > - VM_BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE * nr); > + __bio_add_page(bio, page, PAGE_SIZE * hpage_nr_pages(page), 0); > } > return bio; Actually the above code can be simplified as: diff --git a/mm/page_io.c b/mm/page_io.c index 2e8019d0e048..c20b4189d0a1 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -29,7 +29,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags, struct page *page, bio_end_io_t end_io) { - int i, nr = hpage_nr_pages(page); + int nr = hpage_nr_pages(page); struct bio *bio; bio = bio_alloc(gfp_flags, nr); @@ -41,8 +41,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags, bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9; bio->bi_end_io = end_io; - for (i = 0; i < nr; i++) - bio_add_page(bio, page + i, PAGE_SIZE, 0); + bio_add_page(bio, page, PAGE_SIZE * nr, 0); VM_BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE * nr); } return bio; Thanks, Ming
Ming Lei <ming.lei@redhat.com> writes: > Hi Huang Ying, > > On Mon, Jun 24, 2019 at 10:23:36AM +0800, Huang, Ying wrote: >> From: Huang Ying <ying.huang@intel.com> >> >> 0-Day test system reported some OOM regressions for several >> THP (Transparent Huge Page) swap test cases. These regressions are >> bisected to 6861428921b5 ("block: always define BIO_MAX_PAGES as >> 256"). In the commit, BIO_MAX_PAGES is set to 256 even when THP swap >> is enabled. So the bio_alloc(gfp_flags, 512) in get_swap_bio() may >> fail when swapping out THP. That causes the OOM. >> >> As in the patch description of 6861428921b5 ("block: always define >> BIO_MAX_PAGES as 256"), THP swap should use multi-page bvec to write >> THP to swap space. So the issue is fixed via doing that in >> get_swap_bio(). >> >> BTW: I remember I have checked the THP swap code when >> 6861428921b5 ("block: always define BIO_MAX_PAGES as 256") was merged, >> and thought the THP swap code needn't to be changed. But apparently, >> I was wrong. I should have done this at that time. >> >> Fixes: 6861428921b5 ("block: always define BIO_MAX_PAGES as 256") >> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> >> Cc: Ming Lei <ming.lei@redhat.com> >> Cc: Michal Hocko <mhocko@kernel.org> >> Cc: Johannes Weiner <hannes@cmpxchg.org> >> Cc: Hugh Dickins <hughd@google.com> >> Cc: Minchan Kim <minchan@kernel.org> >> Cc: Rik van Riel <riel@redhat.com> >> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> >> --- >> mm/page_io.c | 7 ++----- >> 1 file changed, 2 insertions(+), 5 deletions(-) >> >> diff --git a/mm/page_io.c b/mm/page_io.c >> index 2e8019d0e048..4ab997f84061 100644 >> --- a/mm/page_io.c >> +++ b/mm/page_io.c >> @@ -29,10 +29,9 @@ >> static struct bio *get_swap_bio(gfp_t gfp_flags, >> struct page *page, bio_end_io_t end_io) >> { >> - int i, nr = hpage_nr_pages(page); >> struct bio *bio; >> >> - bio = bio_alloc(gfp_flags, nr); >> + bio = bio_alloc(gfp_flags, 1); >> if (bio) { >> struct block_device *bdev; >> >> @@ -41,9 +40,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags, >> bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9; >> bio->bi_end_io = end_io; >> >> - for (i = 0; i < nr; i++) >> - bio_add_page(bio, page + i, PAGE_SIZE, 0); > > bio_add_page() supposes to work, just wondering why it doesn't recently. Yes. Just checked and bio_add_page() works too. I should have used that. The problem isn't bio_add_page(), but bio_alloc(), because nr == 512 > 256, mempool cannot be used during swapout, so swapout will fail. Best Regards, Huang, Ying > Could you share me one test case for reproducing it? > >> - VM_BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE * nr); >> + __bio_add_page(bio, page, PAGE_SIZE * hpage_nr_pages(page), 0); >> } >> return bio; > > Actually the above code can be simplified as: > > diff --git a/mm/page_io.c b/mm/page_io.c > index 2e8019d0e048..c20b4189d0a1 100644 > --- a/mm/page_io.c > +++ b/mm/page_io.c > @@ -29,7 +29,7 @@ > static struct bio *get_swap_bio(gfp_t gfp_flags, > struct page *page, bio_end_io_t end_io) > { > - int i, nr = hpage_nr_pages(page); > + int nr = hpage_nr_pages(page); > struct bio *bio; > > bio = bio_alloc(gfp_flags, nr); > @@ -41,8 +41,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags, > bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9; > bio->bi_end_io = end_io; > > - for (i = 0; i < nr; i++) > - bio_add_page(bio, page + i, PAGE_SIZE, 0); > + bio_add_page(bio, page, PAGE_SIZE * nr, 0); > VM_BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE * nr); > } > return bio; > > > Thanks, > Ming
On Mon, Jun 24, 2019 at 12:44:41PM +0800, Huang, Ying wrote: > Ming Lei <ming.lei@redhat.com> writes: > > > Hi Huang Ying, > > > > On Mon, Jun 24, 2019 at 10:23:36AM +0800, Huang, Ying wrote: > >> From: Huang Ying <ying.huang@intel.com> > >> > >> 0-Day test system reported some OOM regressions for several > >> THP (Transparent Huge Page) swap test cases. These regressions are > >> bisected to 6861428921b5 ("block: always define BIO_MAX_PAGES as > >> 256"). In the commit, BIO_MAX_PAGES is set to 256 even when THP swap > >> is enabled. So the bio_alloc(gfp_flags, 512) in get_swap_bio() may > >> fail when swapping out THP. That causes the OOM. > >> > >> As in the patch description of 6861428921b5 ("block: always define > >> BIO_MAX_PAGES as 256"), THP swap should use multi-page bvec to write > >> THP to swap space. So the issue is fixed via doing that in > >> get_swap_bio(). > >> > >> BTW: I remember I have checked the THP swap code when > >> 6861428921b5 ("block: always define BIO_MAX_PAGES as 256") was merged, > >> and thought the THP swap code needn't to be changed. But apparently, > >> I was wrong. I should have done this at that time. > >> > >> Fixes: 6861428921b5 ("block: always define BIO_MAX_PAGES as 256") > >> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> > >> Cc: Ming Lei <ming.lei@redhat.com> > >> Cc: Michal Hocko <mhocko@kernel.org> > >> Cc: Johannes Weiner <hannes@cmpxchg.org> > >> Cc: Hugh Dickins <hughd@google.com> > >> Cc: Minchan Kim <minchan@kernel.org> > >> Cc: Rik van Riel <riel@redhat.com> > >> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> > >> --- > >> mm/page_io.c | 7 ++----- > >> 1 file changed, 2 insertions(+), 5 deletions(-) > >> > >> diff --git a/mm/page_io.c b/mm/page_io.c > >> index 2e8019d0e048..4ab997f84061 100644 > >> --- a/mm/page_io.c > >> +++ b/mm/page_io.c > >> @@ -29,10 +29,9 @@ > >> static struct bio *get_swap_bio(gfp_t gfp_flags, > >> struct page *page, bio_end_io_t end_io) > >> { > >> - int i, nr = hpage_nr_pages(page); > >> struct bio *bio; > >> > >> - bio = bio_alloc(gfp_flags, nr); > >> + bio = bio_alloc(gfp_flags, 1); > >> if (bio) { > >> struct block_device *bdev; > >> > >> @@ -41,9 +40,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags, > >> bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9; > >> bio->bi_end_io = end_io; > >> > >> - for (i = 0; i < nr; i++) > >> - bio_add_page(bio, page + i, PAGE_SIZE, 0); > > > > bio_add_page() supposes to work, just wondering why it doesn't recently. > > Yes. Just checked and bio_add_page() works too. I should have used > that. The problem isn't bio_add_page(), but bio_alloc(), because nr == > 512 > 256, mempool cannot be used during swapout, so swapout will fail. Then we can pass 1 to bio_alloc(), together with single bio_add_page() for making the code more readable. thanks, Ming
Ming Lei <ming.lei@redhat.com> writes: > On Mon, Jun 24, 2019 at 12:44:41PM +0800, Huang, Ying wrote: >> Ming Lei <ming.lei@redhat.com> writes: >> >> > Hi Huang Ying, >> > >> > On Mon, Jun 24, 2019 at 10:23:36AM +0800, Huang, Ying wrote: >> >> From: Huang Ying <ying.huang@intel.com> >> >> >> >> 0-Day test system reported some OOM regressions for several >> >> THP (Transparent Huge Page) swap test cases. These regressions are >> >> bisected to 6861428921b5 ("block: always define BIO_MAX_PAGES as >> >> 256"). In the commit, BIO_MAX_PAGES is set to 256 even when THP swap >> >> is enabled. So the bio_alloc(gfp_flags, 512) in get_swap_bio() may >> >> fail when swapping out THP. That causes the OOM. >> >> >> >> As in the patch description of 6861428921b5 ("block: always define >> >> BIO_MAX_PAGES as 256"), THP swap should use multi-page bvec to write >> >> THP to swap space. So the issue is fixed via doing that in >> >> get_swap_bio(). >> >> >> >> BTW: I remember I have checked the THP swap code when >> >> 6861428921b5 ("block: always define BIO_MAX_PAGES as 256") was merged, >> >> and thought the THP swap code needn't to be changed. But apparently, >> >> I was wrong. I should have done this at that time. >> >> >> >> Fixes: 6861428921b5 ("block: always define BIO_MAX_PAGES as 256") >> >> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> >> >> Cc: Ming Lei <ming.lei@redhat.com> >> >> Cc: Michal Hocko <mhocko@kernel.org> >> >> Cc: Johannes Weiner <hannes@cmpxchg.org> >> >> Cc: Hugh Dickins <hughd@google.com> >> >> Cc: Minchan Kim <minchan@kernel.org> >> >> Cc: Rik van Riel <riel@redhat.com> >> >> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> >> >> --- >> >> mm/page_io.c | 7 ++----- >> >> 1 file changed, 2 insertions(+), 5 deletions(-) >> >> >> >> diff --git a/mm/page_io.c b/mm/page_io.c >> >> index 2e8019d0e048..4ab997f84061 100644 >> >> --- a/mm/page_io.c >> >> +++ b/mm/page_io.c >> >> @@ -29,10 +29,9 @@ >> >> static struct bio *get_swap_bio(gfp_t gfp_flags, >> >> struct page *page, bio_end_io_t end_io) >> >> { >> >> - int i, nr = hpage_nr_pages(page); >> >> struct bio *bio; >> >> >> >> - bio = bio_alloc(gfp_flags, nr); >> >> + bio = bio_alloc(gfp_flags, 1); >> >> if (bio) { >> >> struct block_device *bdev; >> >> >> >> @@ -41,9 +40,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags, >> >> bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9; >> >> bio->bi_end_io = end_io; >> >> >> >> - for (i = 0; i < nr; i++) >> >> - bio_add_page(bio, page + i, PAGE_SIZE, 0); >> > >> > bio_add_page() supposes to work, just wondering why it doesn't recently. >> >> Yes. Just checked and bio_add_page() works too. I should have used >> that. The problem isn't bio_add_page(), but bio_alloc(), because nr == >> 512 > 256, mempool cannot be used during swapout, so swapout will fail. > > Then we can pass 1 to bio_alloc(), together with single bio_add_page() > for making the code more readable. > Yes. Will send out v2 to replace __bio_add_page() with bio_add_page(). Best Regards, Huang, Ying
diff --git a/mm/page_io.c b/mm/page_io.c index 2e8019d0e048..4ab997f84061 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -29,10 +29,9 @@ static struct bio *get_swap_bio(gfp_t gfp_flags, struct page *page, bio_end_io_t end_io) { - int i, nr = hpage_nr_pages(page); struct bio *bio; - bio = bio_alloc(gfp_flags, nr); + bio = bio_alloc(gfp_flags, 1); if (bio) { struct block_device *bdev; @@ -41,9 +40,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags, bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9; bio->bi_end_io = end_io; - for (i = 0; i < nr; i++) - bio_add_page(bio, page + i, PAGE_SIZE, 0); - VM_BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE * nr); + __bio_add_page(bio, page, PAGE_SIZE * hpage_nr_pages(page), 0); } return bio; }