mm/page_alloc: Always attempt to allocate at least one page during bulk allocation
Subsystems (4)
PATCH 1/1 mm/page_alloc: Always attempt to allocate at least one page during bulk allocation
Peter Pavlisko reported the following problem on kernel bugzilla 216007.
When I try to extract an uncompressed tar archive (2.6 milion files, 760.3 GiB in size) on newly created (empty) XFS file system, after first low tens of gigabytes extracted the process hangs in iowait indefinitely. One CPU core is 100% occupied with iowait, the other CPU core is idle (on 2-core Intel Celeron G1610T).
It was bisected to c9fa563072e1 ("xfs: use alloc_pages_bulk_array() for buffers") but XFS is only the messenger. The problem is that nothing is waking kswapd to reclaim some pages at a time the PCP lists cannot be refilled until some reclaim happens. The bulk allocator checks that there are some pages in the array and the original intent was that a bulk allocator did not necessarily need all the requested pages and it was best to return as quickly as possible. This was fine for the first user of the API but both NFS and XFS require the requested number of pages be available before making progress. Both could be adjusted to call the page allocator directly if a bulk allocation fails but it puts a burden on users of the API. Adjust the semantics to attempt at least one allocation via __alloc_pages() before returning so kswapd is woken if necessary.
It was reported via bugzilla that the patch addressed the problem and that the tar extraction completed successfully. This may also address bug 215975 but has yet to be confirmed.
--- mm/page_alloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
mm/page_alloc.c +2 -2
@@ -5324,8 +5324,8 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, page =__rmqueue_pcplist (zone,0 , ac.migratetype, alloc_flags, pcp, pcp_list);if (unlikely (!page)) { -/* Try and get at least one page */ -if (!nr_populated) +/* Try and allocate at least one page */ +if (!nr_account) goto failed_irq;break ; }
Quoted 39 lines · Mel Gorman
Peter Pavlisko reported the following problem on kernel bugzilla 216007.
When I try to extract an uncompressed tar archive (2.6 milion files, 760.3 GiB in size) on newly created (empty) XFS file system, after first low tens of gigabytes extracted the process hangs in iowait indefinitely. One CPU core is 100% occupied with iowait, the other CPU core is idle (on 2-core Intel Celeron G1610T).
It was bisected to
c9fa563072e1("xfs: usealloc_pages_bulk_array()for buffers") but XFS is only the messenger. The problem is that nothing is waking kswapd to reclaim some pages at a time the PCP lists cannot be refilled until some reclaim happens. The bulk allocator checks that there are some pages in the array and the original intent was that a bulk allocator did not necessarily need all the requested pages and it was best to return as quickly as possible. This was fine for the first user of the API but both NFS and XFS require the requested number of pages be available before making progress. Both could be adjusted to call the page allocator directly if a bulk allocation fails but it puts a burden on users of the API. Adjust the semantics to attempt at least one allocation via__alloc_pages()before returning so kswapd is woken if necessary.It was reported via bugzilla that the patch addressed the problem and that the tar extraction completed successfully. This may also address bug 215975 but has yet to be confirmed.
Fixes 387ba26fb1cb ("mm/page_alloc: add a bulk page allocator")Signed-off-by Mel Gorman <[email protected]>Cc <[email protected]> # v5.13+--- mm/page_alloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)mm/page_alloc.c +0
-0
mm/page_alloc.c unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, · line 5331
Quoted 10 lines
mm/page_alloc.c +2
-2@@ -5324,8 +5324,8 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, page =__rmqueue_pcplist (zone,0 , ac.migratetype, alloc_flags, pcp, pcp_list);if (unlikely (!page)) { -/* Try and get at least one page */ -if (!nr_populated) +/* Try and allocate at least one page */ +if (!nr_account) goto failed_irq;break ; }
Looks like a sane fix to me.
Signature · 2 lines
Dave Chinner [email protected]
Quoted 29 lines · Mel Gorman
Peter Pavlisko reported the following problem on kernel bugzilla 216007.
When I try to extract an uncompressed tar archive (2.6 milion files, 760.3 GiB in size) on newly created (empty) XFS file system, after first low tens of gigabytes extracted the process hangs in iowait indefinitely. One CPU core is 100% occupied with iowait, the other CPU core is idle (on 2-core Intel Celeron G1610T).
It was bisected to
c9fa563072e1("xfs: usealloc_pages_bulk_array()for buffers") but XFS is only the messenger. The problem is that nothing is waking kswapd to reclaim some pages at a time the PCP lists cannot be refilled until some reclaim happens. The bulk allocator checks that there are some pages in the array and the original intent was that a bulk allocator did not necessarily need all the requested pages and it was best to return as quickly as possible. This was fine for the first user of the API but both NFS and XFS require the requested number of pages be available before making progress. Both could be adjusted to call the page allocator directly if a bulk allocation fails but it puts a burden on users of the API. Adjust the semantics to attempt at least one allocation via__alloc_pages()before returning so kswapd is woken if necessary.It was reported via bugzilla that the patch addressed the problem and that the tar extraction completed successfully. This may also address bug 215975 but has yet to be confirmed.
Quoted 5 lines
Fixes 387ba26fb1cb ("mm/page_alloc: add a bulk page allocator")Signed-off-by Mel Gorman <[email protected]>Cc <[email protected]> # v5.13+
Fwiw, Reviewed-by: Chuck Lever <[email protected]>
Quoted 9 lines
---
mm/page_alloc.c| 4 ++--1 file changed, 2 insertions(+), 2 deletions(-)mm/page_alloc.c +0
-0
mm/page_alloc.c unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, · line 5331
Quoted 10 lines
mm/page_alloc.c +2
-2@@ -5324,8 +5324,8 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, page =__rmqueue_pcplist (zone,0 , ac.migratetype, alloc_flags, pcp, pcp_list);if (unlikely (!page)) { -/* Try and get at least one page */ -if (!nr_populated) +/* Try and allocate at least one page */ +if (!nr_account) goto failed_irq;break ; }
--
Chuck Lever
Quoted 25 lines · Mel Gorman
Peter Pavlisko reported the following problem on kernel bugzilla 216007.
When I try to extract an uncompressed tar archive (2.6 milion files, 760.3 GiB in size) on newly created (empty) XFS file system, after first low tens of gigabytes extracted the process hangs in iowait indefinitely. One CPU core is 100% occupied with iowait, the other CPU core is idle (on 2-core Intel Celeron G1610T).
It was bisected to
c9fa563072e1("xfs: usealloc_pages_bulk_array()for buffers") but XFS is only the messenger. The problem is that nothing is waking kswapd to reclaim some pages at a time the PCP lists cannot be refilled until some reclaim happens. The bulk allocator checks that there are some pages in the array and the original intent was that a bulk allocator did not necessarily need all the requested pages and it was best to return as quickly as possible. This was fine for the first user of the API but both NFS and XFS require the requested number of pages be available before making progress. Both could be adjusted to call the page allocator directly if a bulk allocation fails but it puts a burden on users of the API. Adjust the semantics to attempt at least one allocation via__alloc_pages()before returning so kswapd is woken if necessary.It was reported via bugzilla that the patch addressed the problem and that the tar extraction completed successfully. This may also address bug 215975 but has yet to be confirmed.
Quoted 5 lines
Fixes 387ba26fb1cb ("mm/page_alloc: add a bulk page allocator")Signed-off-by Mel Gorman <[email protected]>Cc <[email protected]> # v5.13+
Seems to have survived overnight fstests on XFS, so...
--D
Quoted 19 lines
--- mm/page_alloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)mm/page_alloc.c +2
-2@@ -5324,8 +5324,8 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, page =__rmqueue_pcplist (zone,0 , ac.migratetype, alloc_flags, pcp, pcp_list);if (unlikely (!page)) { -/* Try and get at least one page */ -if (!nr_populated) +/* Try and allocate at least one page */ +if (!nr_account) goto failed_irq;break ; }
Quoted 25 lines · Mel Gorman
Peter Pavlisko reported the following problem on kernel bugzilla 216007.
When I try to extract an uncompressed tar archive (2.6 milion files, 760.3 GiB in size) on newly created (empty) XFS file system, after first low tens of gigabytes extracted the process hangs in iowait indefinitely. One CPU core is 100% occupied with iowait, the other CPU core is idle (on 2-core Intel Celeron G1610T).
It was bisected to
c9fa563072e1("xfs: usealloc_pages_bulk_array()for buffers") but XFS is only the messenger. The problem is that nothing is waking kswapd to reclaim some pages at a time the PCP lists cannot be refilled until some reclaim happens. The bulk allocator checks that there are some pages in the array and the original intent was that a bulk allocator did not necessarily need all the requested pages and it was best to return as quickly as possible. This was fine for the first user of the API but both NFS and XFS require the requested number of pages be available before making progress. Both could be adjusted to call the page allocator directly if a bulk allocation fails but it puts a burden on users of the API. Adjust the semantics to attempt at least one allocation via__alloc_pages()before returning so kswapd is woken if necessary.It was reported via bugzilla that the patch addressed the problem and that the tar extraction completed successfully. This may also address bug 215975 but has yet to be confirmed.
Quoted 8 lines
Fixes 387ba26fb1cb ("mm/page_alloc: add a bulk page allocator")Signed-off-by Mel Gorman <[email protected]>Cc <[email protected]> # v5.13+--- mm/page_alloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
Change looks good, and I checked page_pool will be fine with this change :-)
Quoted 16 lines
mm/page_alloc.c +2
-2@@ -5324,8 +5324,8 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, page =__rmqueue_pcplist (zone,0 , ac.migratetype, alloc_flags, pcp, pcp_list);if (unlikely (!page)) { -/* Try and get at least one page */ -if (!nr_populated) +/* Try and allocate at least one page */ +if (!nr_account) goto failed_irq;break ; }