From: Oscar Salvador <osalvador@suse.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
David Hildenbrand <david@redhat.com>,
Muchun Song <songmuchun@bytedance.com>,
Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Oscar Salvador <osalvador@suse.de>
Subject: [PATCH v3 0/2] Make alloc_contig_range handle Hugetlb pages
Date: Mon, 22 Feb 2021 14:51:35 +0100 [thread overview]
Message-ID: <20210222135137.25717-1-osalvador@suse.de> (raw)
v2 -> v3:
- Drop usage of high-level generic helpers in favour of
low-level approach (per Michal)
- Check for the page to be marked as PageHugeFreed
- Add a one-time retry in case someone grabbed the free huge page
from under us
v1 -> v2:
- Adressed feedback by Michal
- Restrict the allocation to a node with __GFP_THISNODE
- Drop PageHuge check in alloc_and_dissolve_huge_page
- Re-order comments in isolate_or_dissolve_huge_page
- Extend comment in isolate_migratepages_block
- Place put_page right after we got the page, otherwise
dissolve_free_huge_page will fail
RFC -> v1:
- Drop RFC
- Addressed feedback from David and Mike
- Fence off gigantic pages as there is a cyclic dependency between
them and alloc_contig_range
- Re-organize the code to make race-window smaller and to put
all details in hugetlb code
- Drop nodemask initialization. First a node will be tried and then we
will back to other nodes containing memory (N_MEMORY). Details in
patch#1's changelog
- Count new page as surplus in case we failed to dissolve the old page
and the new one. Details in patch#1.
Cover letter:
alloc_contig_range lacks the hability for handling HugeTLB pages.
This can be problematic for some users, e.g: CMA and virtio-mem, where those
users will fail the call if alloc_contig_range ever sees a HugeTLB page, even
when those pages lay in ZONE_MOVABLE and are free.
That problem can be easily solved by replacing the page in the free hugepage
pool.
In-use HugeTLB are no exception though, as those can be isolated and migrated
as any other LRU or Movable page.
This patchset aims for improving alloc_contig_range->isolate_migratepages_block,
so HugeTLB pages can be recognized and handled.
Below is an insight from David (thanks), where the problem can clearly be seen:
"Start a VM with 4G. Hotplug 1G via virtio-mem and online it to
ZONE_MOVABLE. Allocate 512 huge pages.
[root@localhost ~]# cat /proc/meminfo
MemTotal: 5061512 kB
MemFree: 3319396 kB
MemAvailable: 3457144 kB
...
HugePages_Total: 512
HugePages_Free: 512
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
The huge pages get partially allocate from ZONE_MOVABLE. Try unplugging
1G via virtio-mem (remember, all ZONE_MOVABLE). Inside the guest:
[ 180.058992] alloc_contig_range: [1b8000, 1c0000) PFNs busy
[ 180.060531] alloc_contig_range: [1b8000, 1c0000) PFNs busy
[ 180.061972] alloc_contig_range: [1b8000, 1c0000) PFNs busy
[ 180.063413] alloc_contig_range: [1b8000, 1c0000) PFNs busy
[ 180.064838] alloc_contig_range: [1b8000, 1c0000) PFNs busy
[ 180.065848] alloc_contig_range: [1bfc00, 1c0000) PFNs busy
[ 180.066794] alloc_contig_range: [1bfc00, 1c0000) PFNs busy
[ 180.067738] alloc_contig_range: [1bfc00, 1c0000) PFNs busy
[ 180.068669] alloc_contig_range: [1bfc00, 1c0000) PFNs busy
[ 180.069598] alloc_contig_range: [1bfc00, 1c0000) PFNs busy"
Oscar Salvador (2):
mm: Make alloc_contig_range handle free hugetlb pages
mm: Make alloc_contig_range handle in-use hugetlb pages
include/linux/hugetlb.h | 7 +++
mm/compaction.c | 22 +++++++++
mm/hugetlb.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++-
mm/vmscan.c | 5 +-
4 files changed, 154 insertions(+), 4 deletions(-)
--
2.16.3
next reply other threads:[~2021-02-22 13:51 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-22 13:51 Oscar Salvador [this message]
2021-02-22 13:51 ` [PATCH v3 1/2] mm: Make alloc_contig_range handle free hugetlb pages Oscar Salvador
2021-02-25 20:03 ` Mike Kravetz
2021-02-26 9:48 ` Oscar Salvador
2021-02-26 8:35 ` Michal Hocko
2021-02-26 8:38 ` Michal Hocko
2021-02-26 9:25 ` David Hildenbrand
2021-02-26 9:47 ` Oscar Salvador
2021-02-26 9:45 ` Oscar Salvador
2021-02-26 9:51 ` Michal Hocko
2021-03-01 14:09 ` David Hildenbrand
2021-03-04 10:19 ` Oscar Salvador
2021-03-04 10:32 ` David Hildenbrand
2021-03-04 10:41 ` Oscar Salvador
2021-02-22 13:51 ` [PATCH v3 2/2] mm: Make alloc_contig_range handle in-use " Oscar Salvador
2021-02-25 23:05 ` Mike Kravetz
2021-02-26 8:46 ` Michal Hocko
2021-02-26 10:24 ` Oscar Salvador
2021-02-26 10:27 ` Oscar Salvador
2021-02-26 12:46 ` Michal Hocko
2021-02-28 13:43 ` Oscar Salvador
2021-03-05 17:30 ` David Hildenbrand
2021-03-01 12:43 ` [PATCH v3 0/2] Make alloc_contig_range handle Hugetlb pages David Hildenbrand
2021-03-01 12:57 ` Oscar Salvador
2021-03-01 12:59 ` David Hildenbrand
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