kernel/git/stable/linux.git/mm/migrate.c, branch linux-5.12.y

mm: migrate: fix missing update page_private to hugetlb_page_subpool

2021-07-14T15:00:28+00:00

[ Upstream commit 6acfb5ba150cf75005ce85e0e25d79ef2fec287c ] Since commit d6995da31122 ("hugetlb: use page.private for hugetlb specific page flags") converts page.private for hugetlb specific page flags. We should use hugetlb_page_subpool() to get the subpool pointer instead of page_private(). This 'could' prevent the migration of hugetlb pages. page_private(hpage) is now used for hugetlb page specific flags. At migration time, the only flag which could be set is HPageVmemmapOptimized. This flag will only be set if the new vmemmap reduction feature is enabled. In addition, !page_mapping() implies an anonymous mapping. So, this will prevent migration of hugetb pages in anonymous mappings if the vmemmap reduction feature is enabled. In addition, that if statement checked for the rare race condition of a page being migrated while in the process of being freed. Since that check is now wrong, we could leak hugetlb subpool usage counts. The commit forgot to update it in the page migration routine. So fix it. [songmuchun@bytedance.com: fix compiler error when !CONFIG_HUGETLB_PAGE reported by Randy] Link: https://lkml.kernel.org/r/20210521022747.35736-1-songmuchun@bytedance.com Link: https://lkml.kernel.org/r/20210520025949.1866-1-songmuchun@bytedance.com Fixes: d6995da31122 ("hugetlb: use page.private for hugetlb specific page flags") Signed-off-by: Muchun Song Reported-by: Anshuman Khandual Reviewed-by: Mike Kravetz Acked-by: Michal Hocko Tested-by: Anshuman Khandual [arm64] Cc: Oscar Salvador Cc: David Hildenbrand Cc: Matthew Wilcox Cc: Xiongchun Duan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

mm, thp: use head page in __migration_entry_wait()

2021-06-30T12:47:05+00:00

commit ffc90cbb2970ab88b66ea51dd580469eede57b67 upstream. We notice that hung task happens in a corner but practical scenario when CONFIG_PREEMPT_NONE is enabled, as follows. Process 0 Process 1 Process 2..Inf split_huge_page_to_list unmap_page split_huge_pmd_address __migration_entry_wait(head) __migration_entry_wait(tail) remap_page (roll back) remove_migration_ptes rmap_walk_anon cond_resched Where __migration_entry_wait(tail) is occurred in kernel space, e.g., copy_to_user in fstat, which will immediately fault again without rescheduling, and thus occupy the cpu fully. When there are too many processes performing __migration_entry_wait on tail page, remap_page will never be done after cond_resched. This makes __migration_entry_wait operate on the compound head page, thus waits for remap_page to complete, whether the THP is split successfully or roll back. Note that put_and_wait_on_page_locked helps to drop the page reference acquired with get_page_unless_zero, as soon as the page is on the wait queue, before actually waiting. So splitting the THP is only prevented for a brief interval. Link: https://lkml.kernel.org/r/b9836c1dd522e903891760af9f0c86a2cce987eb.1623144009.git.xuyu@linux.alibaba.com Fixes: ba98828088ad ("thp: add option to setup migration entries during PMD split") Suggested-by: Hugh Dickins Signed-off-by: Gang Deng Signed-off-by: Xu Yu Acked-by: Kirill A. Shutemov Acked-by: Hugh Dickins Cc: Matthew Wilcox Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm/migrate.c: fix potential indeterminate pte entry in migrate_vma_insert_page()

2021-05-19T08:56:30+00:00

[ Upstream commit 34f5e9b9d1990d286199084efa752530ee3d8297 ] If the zone device page does not belong to un-addressable device memory, the variable entry will be uninitialized and lead to indeterminate pte entry ultimately. Fix this unexpected case and warn about it. Link: https://lkml.kernel.org/r/20210325131524.48181-4-linmiaohe@huawei.com Fixes: df6ad69838fc ("mm/device-public-memory: device memory cache coherent with CPU") Signed-off-by: Miaohe Lin Reviewed-by: David Hildenbrand Cc: Alistair Popple Cc: Jerome Glisse Cc: Rafael Aquini Cc: Yang Shi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

mm: memcg: add swapcache stat for memcg v2

2021-02-24T21:38:29+00:00

This patch adds swapcache stat for the cgroup v2. The swapcache represents the memory that is accounted against both the memory and the swap limit of the cgroup. The main motivation behind exposing the swapcache stat is for enabling users to gracefully migrate from cgroup v1's memsw counter to cgroup v2's memory and swap counters. Cgroup v1's memsw limit allows users to limit the memory+swap usage of a workload but without control on the exact proportion of memory and swap. Cgroup v2 provides separate limits for memory and swap which enables more control on the exact usage of memory and swap individually for the workload. With some little subtleties, the v1's memsw limit can be switched with the sum of the v2's memory and swap limits. However the alternative for memsw usage is not yet available in cgroup v2. Exposing per-cgroup swapcache stat enables that alternative. Adding the memory usage and swap usage and subtracting the swapcache will approximate the memsw usage. This will help in the transparent migration of the workloads depending on memsw usage and limit to v2' memory and swap counters. The reasons these applications are still interested in this approximate memsw usage are: (1) these applications are not really interested in two separate memory and swap usage metrics. A single usage metric is more simple to use and reason about for them. (2) The memsw usage metric hides the underlying system's swap setup from the applications. Applications with multiple instances running in a datacenter with heterogeneous systems (some have swap and some don't) will keep seeing a consistent view of their usage. [akpm@linux-foundation.org: fix CONFIG_SWAP=n build] Link: https://lkml.kernel.org/r/20210108155813.2914586-3-shakeelb@google.com Signed-off-by: Shakeel Butt Acked-by: Michal Hocko Reviewed-by: Roman Gushchin Cc: Johannes Weiner Cc: Muchun Song Cc: Yang Shi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/filemap: pass a sleep state to put_and_wait_on_page_locked

2021-02-24T21:38:28+00:00

This is prep work for the next patch, but I think at least one of the current callers would prefer a killable sleep to an uninterruptible one. Link: https://lkml.kernel.org/r/20210122160140.223228-6-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Kent Overstreet Reviewed-by: Christoph Hellwig Cc: Miaohe Lin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: migrate: do not migrate HugeTLB page whose refcount is one

2021-02-05T19:03:47+00:00

All pages isolated for the migration have an elevated reference count and therefore seeing a reference count equal to 1 means that the last user of the page has dropped the reference and the page has became unused and there doesn't make much sense to migrate it anymore. This has been done for regular pages and this patch does the same for hugetlb pages. Although the likelihood of the race is rather small for hugetlb pages it makes sense the two code paths in sync. Link: https://lkml.kernel.org/r/20210115124942.46403-2-songmuchun@bytedance.com Signed-off-by: Muchun Song Reviewed-by: Mike Kravetz Acked-by: Yang Shi Acked-by: Michal Hocko Reviewed-by: David Hildenbrand Reviewed-by: Oscar Salvador Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: fix numa stats for thp migration

2021-01-24T17:20:52+00:00

Currently the kernel is not correctly updating the numa stats for NR_FILE_PAGES and NR_SHMEM on THP migration. Fix that. For NR_FILE_DIRTY and NR_ZONE_WRITE_PENDING, although at the moment there is no need to handle THP migration as kernel still does not have write support for file THP but to be more future proof, this patch adds the THP support for those stats as well. Link: https://lkml.kernel.org/r/20210108155813.2914586-2-shakeelb@google.com Fixes: e71769ae52609 ("mm: enable thp migration for shmem thp") Signed-off-by: Shakeel Butt Acked-by: Yang Shi Reviewed-by: Roman Gushchin Cc: Johannes Weiner Cc: Michal Hocko Cc: Muchun Song Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: memcg: fix memcg file_dirty numa stat

2021-01-24T17:20:52+00:00

The kernel updates the per-node NR_FILE_DIRTY stats on page migration but not the memcg numa stats. That was not an issue until recently the commit 5f9a4f4a7096 ("mm: memcontrol: add the missing numa_stat interface for cgroup v2") exposed numa stats for the memcg. So fix the file_dirty per-memcg numa stat. Link: https://lkml.kernel.org/r/20210108155813.2914586-1-shakeelb@google.com Fixes: 5f9a4f4a7096 ("mm: memcontrol: add the missing numa_stat interface for cgroup v2") Signed-off-by: Shakeel Butt Reviewed-by: Muchun Song Acked-by: Yang Shi Reviewed-by: Roman Gushchin Cc: Johannes Weiner Cc: Michal Hocko Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: fix some spelling mistakes in comments

2020-12-16T06:46:19+00:00

Fix some spelling mistakes in comments: udpate ==> update succesful ==> successful exmaple ==> example unneccessary ==> unnecessary stoping ==> stopping uknown ==> unknown Link: https://lkml.kernel.org/r/20201127011747.86005-1-shihaitao1@huawei.com Signed-off-by: Haitao Shi Reviewed-by: Mike Rapoport Reviewed-by: Souptick Joarder Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: migrate: remove unused parameter in migrate_vma_insert_page()

2020-12-15T20:13:46+00:00

"dst" parameter to migrate_vma_insert_page() is not used anymore. Link: https://lkml.kernel.org/r/CANubcdUwCAMuUyamG2dkWP=cqSR9MAS=tHLDc95kQkqU-rEnAg@mail.gmail.com Signed-off-by: Stephen Zhang Reviewed-by: David Hildenbrand Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds