- 18 Aug, 2023 40 commits
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Matthew Wilcox (Oracle) authored
The primary goal here is removing the use of set_bh_page(). Take the opportunity to switch from kmap_atomic() to kmap_local(). This simplifies the function as the offset is already added to the pointer. Link: https://lkml.kernel.org/r/20230713035512.4139457-7-willy@infradead.orgSigned-off-by:
Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by:
Jan Kara <jack@suse.cz> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: David Sterba <dsterba@suse.com> Cc: Konstantin Komarov <almaz.alexandrovich@paragon-software.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Pankaj Raghav <p.raghav@samsung.com> Cc: Tom Rix <trix@redhat.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org>
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Matthew Wilcox (Oracle) authored
Remove a user of set_bh_page(). Link: https://lkml.kernel.org/r/20230713035512.4139457-6-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
This function was converted before folio_set_bh() existed. Catch up to the new API. Link: https://lkml.kernel.org/r/20230713035512.4139457-5-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
We still need to convert to/from folios in write_begin & write_end to fit the API, but this removes a lot of calls to old page-based functions, removing many hidden calls to compound_head(). Link: https://lkml.kernel.org/r/20230713035512.4139457-4-willy@infradead.orgSigned-off-by:
Pankaj Raghav <p.raghav@samsung.com> Acked-by:
David Sterba <dsterba@suse.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: Jan Kara <jack@suse.com> Cc: Konstantin Komarov <almaz.alexandrovich@paragon-software.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Tom Rix <trix@redhat.com> Signed-off-by:
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Matthew Wilcox (Oracle) authored
Remove use of the old page APIs. That includes use of setting PageError on error; simply not setting the uptodate flag is sufficient. Link: https://lkml.kernel.org/r/20230713035512.4139457-3-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Patch series "More filesystem folio conversions for 6.6". Remove the only spots in affs which actually use a struct page; there are a few places where one is mentioned, but it's part of the interface. The rest of this is removing the remaining calls to set_bh_page(), and then removing the function before any new users show up. This patch (of 7): These are the folio equivalent of memcpy_to_page() and memcpy_from_page(). [agruenba@redhat.com: use correct chunk size in memcpy()] Link: https://lkml.kernel.org/r/20230802144354.1023099-1-agruenba@redhat.com Link: https://lkml.kernel.org/r/20230713035512.4139457-1-willy@infradead.org Link: https://lkml.kernel.org/r/20230713035512.4139457-2-willy@infradead.orgSigned-off-by:
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Kemeng Shi authored
Remove unused addr in __page_table_check_pud_set and page_table_check_pud_set. Link: https://lkml.kernel.org/r/20230713172636.1705415-9-shikemeng@huaweicloud.comSigned-off-by:
Kemeng Shi <shikemeng@huaweicloud.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by:
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Kemeng Shi authored
Remove unused addr in __page_table_check_pmd_set and page_table_check_pmd_set. Link: https://lkml.kernel.org/r/20230713172636.1705415-8-shikemeng@huaweicloud.comSigned-off-by:
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Kemeng Shi authored
Remove unused addr in __page_table_check_pte_set and page_table_check_pte_set. Link: https://lkml.kernel.org/r/20230713172636.1705415-7-shikemeng@huaweicloud.comSigned-off-by:
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Kemeng Shi authored
Remove unused addr in __page_table_check_pud_clear and page_table_check_pud_clear. Link: https://lkml.kernel.org/r/20230713172636.1705415-6-shikemeng@huaweicloud.comSigned-off-by:
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Kemeng Shi authored
Remove unused addr in page_table_check_pmd_clear and __page_table_check_pmd_clear. Link: https://lkml.kernel.org/r/20230713172636.1705415-5-shikemeng@huaweicloud.comSigned-off-by:
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Kemeng Shi authored
Remove unused addr in page_table_check_pte_clear and __page_table_check_pte_clear. Link: https://lkml.kernel.org/r/20230713172636.1705415-4-shikemeng@huaweicloud.comSigned-off-by:
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Kemeng Shi authored
Remove unused mm and addr in page_table_check_set(). Link: https://lkml.kernel.org/r/20230713172636.1705415-3-shikemeng@huaweicloud.comSigned-off-by:
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Kemeng Shi authored
Patch series "Remove unused parameters in page_table_check". This series remove unused parameters in functions from page_table_check. The first 2 patches remove unused mm and addr parameters in static common functions page_table_check_clear and page_table_check_set. The last 6 patches remove unused addr parameter in some externed functions which only need addr for cleaned page_table_check_clear or page_table_check_set. There is no intended functional change. This patch (of 8): Remove unused mm and addr in function page_table_check_clear(). Link: https://lkml.kernel.org/r/20230713172636.1705415-1-shikemeng@huaweicloud.com Link: https://lkml.kernel.org/r/20230713172636.1705415-2-shikemeng@huaweicloud.comSigned-off-by:
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Miaohe Lin authored
Since commit 5660048c ("mm: move memcg hierarchy reclaim to generic reclaim code"), mem_cgroup_hierarchical_reclaim() is already renamed to mem_cgroup_soft_reclaim(). Update the corresponding comment. Link: https://lkml.kernel.org/r/20230713121432.273381-1-linmiaohe@huawei.comSigned-off-by:
Miaohe Lin <linmiaohe@huawei.com> Reviewed-by:
Muchun Song <songmuchun@bytedance.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by:
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Miaohe Lin authored
It's more convenient and readable to use RMAP_NONE instead of false when calling page_add_anon_rmap(). No functional change intended. Link: https://lkml.kernel.org/r/20230713120557.218592-1-linmiaohe@huawei.comSigned-off-by:
David Hildenbrand <david@redhat.com> Reviewed-by:
Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by:
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Jiaqi Yan authored
Add tests for the improvement made to read operation on HWPOISON hugetlb page with different read granularities. For each chunk size, three read scenarios are tested: 1. Simple regression test on read without HWPOISON. 2. Sequential read page by page should succeed until encounters the 1st raw HWPOISON subpage. 3. After skip a raw HWPOISON subpage by lseek, read()s always succeed. Link: https://lkml.kernel.org/r/20230713001833.3778937-5-jiaqiyan@google.comSigned-off-by:
Jiaqi Yan <jiaqiyan@google.com> Acked-by:
Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by:
Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: James Houghton <jthoughton@google.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by:
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Jiaqi Yan authored
When a hugepage contains HWPOISON pages, read() fails to read any byte of the hugepage and returns -EIO, although many bytes in the HWPOISON hugepage are readable. Improve this by allowing hugetlbfs_read_iter returns as many bytes as possible. For a requested range [offset, offset + len) that contains HWPOISON page, return [offset, first HWPOISON page addr); the next read attempt will fail and return -EIO. Link: https://lkml.kernel.org/r/20230713001833.3778937-4-jiaqiyan@google.comSigned-off-by:
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Jiaqi Yan authored
Add the functionality, is_raw_hwpoison_page_in_hugepage, to tell if a raw page in a hugetlb folio is HWPOISON. This functionality relies on RawHwpUnreliable to be not set; otherwise hugepage's raw HWPOISON list becomes meaningless. is_raw_hwpoison_page_in_hugepage holds mf_mutex in order to synchronize with folio_set_hugetlb_hwpoison and folio_free_raw_hwp who iterate, insert, or delete entry in raw_hwp_list. llist itself doesn't ensure insertion and removal are synchornized with the llist_for_each_entry used by is_raw_hwpoison_page_in_hugepage (unless iterated entries are already deleted from the list). Caller can minimize the overhead of lock cycles by first checking HWPOISON flag of the folio. Exports this functionality to be immediately used in the read operation for hugetlbfs. Link: https://lkml.kernel.org/r/20230713001833.3778937-3-jiaqiyan@google.comSigned-off-by:
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Jiaqi Yan authored
Patch series "Improve hugetlbfs read on HWPOISON hugepages", v4. Today when hardware memory is corrupted in a hugetlb hugepage, kernel leaves the hugepage in pagecache [1]; otherwise future mmap or read will suject to silent data corruption. This is implemented by returning -EIO from hugetlb_read_iter immediately if the hugepage has HWPOISON flag set. Since memory_failure already tracks the raw HWPOISON subpages in a hugepage, a natural improvement is possible: if userspace only asks for healthy subpages in the pagecache, kernel can return these data. This patchset implements this improvement. It consist of three parts. The 1st commit exports the functionality to tell if a subpage inside a hugetlb hugepage is a raw HWPOISON page. The 2nd commit teaches hugetlbfs_read_iter to return as many healthy bytes as possible. The 3rd commit properly tests this new feature. [1] commit 8625147c ("hugetlbfs: don't delete error page from pagecache") This patch (of 4): Traversal on llist (e.g. llist_for_each_safe) is only safe AFTER entries are deleted from the llist. Correct the way __folio_free_raw_hwp deletes and frees raw_hwp_page entries in raw_hwp_list: first llist_del_all, then kfree within llist_for_each_safe. As of today, concurrent adding, deleting, and traversal on raw_hwp_list from hugetlb.c and/or memory-failure.c are fine with each other. Note this is guaranteed partly by the lock-free nature of llist, and partly by holding hugetlb_lock and/or mf_mutex. For example, as llist_del_all is lock-free with itself, folio_clear_hugetlb_hwpoison()s from __update_and_free_hugetlb_folio and memory_failure won't need explicit locking when freeing the raw_hwp_list. New code that manipulates raw_hwp_list must be careful to ensure the concurrency correctness. Link: https://lkml.kernel.org/r/20230713001833.3778937-1-jiaqiyan@google.com Link: https://lkml.kernel.org/r/20230713001833.3778937-2-jiaqiyan@google.comSigned-off-by:
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Yu Ma authored
UnixBench/Execl represents a class of workload where bash scripts are spawned frequently to do some short jobs. When running multiple parallel tasks, hot osq_lock is observed from do_mmap and exit_mmap. Both of them come from load_elf_binary through the call chain "execl->do_execveat_common->bprm_execve->load_elf_binary". In do_mmap,it will call mmap_region to create vma node, initialize it and insert it to vma maintain structure in mm_struct and i_mmap tree of the mapping file, then increase map_count to record the number of vma nodes used. The hot osq_lock is to protect operations on file's i_mmap tree. For the mm_struct member change like vma insertion and map_count update, they do not affect i_mmap tree. Move those operations out of the lock's critical section, to reduce hold time on the lock. With this change, on Intel Sapphire Rapids 112C/224T platform, based on v6.0-rc6, the 160 parallel score improves by 12%. The patch has no obvious performance gain on v6.5-rc1 due to regression of this benchmark from this commit f1a79412 (mm: convert mm's rss stats into percpu_counter). Related discussion and conclusion can be referred at the mail thread initiated by 0day as below: Link: https://lore.kernel.org/linux-mm/a4aa2e13-7187-600b-c628-7e8fb108def0@intel.com/ Link: https://lkml.kernel.org/r/20230712145739.604215-1-yu.ma@intel.comSigned-off-by:
Yu Ma <yu.ma@intel.com> Reviewed-by:
Tim Chen <tim.c.chen@linux.intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Kirill A . Shutemov <kirill@shutemov.name> Cc: Liam R. Howlett <Liam.Howlett@oracle.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Zhu, Lipeng <lipeng.zhu@intel.com> Signed-off-by:
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Xueshi Hu authored
All callers have now been converted to call folio_clear_idle(). Link: https://lkml.kernel.org/r/20230712134959.145373-1-xueshi.hu@smartx.comSigned-off-by:
Xueshi Hu <xueshi.hu@smartx.com> Reviewed-by:
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Hugh Dickins authored
Add a block of comments on pte_offset_map_lock(), pte_offset_map() and pte_offset_map_nolock() to mm/pgtable-generic.c, to help explain them. Link: https://lkml.kernel.org/r/b791c3b0-25c6-a263-d785-d564344eb644@google.comSigned-off-by:
Hugh Dickins <hughd@google.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Christoph Hellwig <hch@infradead.org> Cc: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Huang, Ying <ying.huang@intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Russell King <linux@armlinux.org.uk> Cc: SeongJae Park <sj@kernel.org> Cc: Song Liu <song@kernel.org> Cc: Steven Price <steven.price@arm.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Cc: Yang Shi <shy828301@gmail.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Zack Rusin <zackr@vmware.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by:
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Hugh Dickins authored
mmap_write_trylock() and vma_try_start_write() were added just for khugepaged, but now it has no use for them: delete. Link: https://lkml.kernel.org/r/4e6db3d-e8e-73fb-1f2a-8de2dab2a87c@google.comSigned-off-by:
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Hugh Dickins authored
Now that retract_page_tables() can retract page tables reliably, without depending on trylocks, delete all the apparatus for khugepaged to try again later: khugepaged_collapse_pte_mapped_thps() etc; and free up the per-mm memory which was set aside for that in the khugepaged_mm_slot. But one part of that is worth keeping: when hpage_collapse_scan_file() found SCAN_PTE_MAPPED_HUGEPAGE, that address was noted in the mm_slot to be tried for retraction later - catching, for example, page tables where a reversible mprotect() of a portion had required splitting the pmd, but now it can be recollapsed. Call collapse_pte_mapped_thp() directly in this case (why was it deferred before? I assume an issue with needing mmap_lock for write, but now it's only needed for read). [hughd@google.com: fix mmap_locked handlng] Link: https://lkml.kernel.org/r/bfc6cab2-497f-32bf-dd5-98dc1987e4a9@google.com Link: https://lkml.kernel.org/r/a5dce57-6dfa-5559-4698-e817eb2f993@google.comSigned-off-by:
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Hugh Dickins authored
Bring collapse_and_free_pmd() back into collapse_pte_mapped_thp(). It does need mmap_read_lock(), but it does not need mmap_write_lock(), nor vma_start_write() nor i_mmap lock nor anon_vma lock. All racing paths are relying on pte_offset_map_lock() and pmd_lock(), so use those. Follow the pattern in retract_page_tables(); and using pte_free_defer() removes most of the need for tlb_remove_table_sync_one() here; but call pmdp_get_lockless_sync() to use it in the PAE case. First check the VMA, in case page tables are being torn down: from JannH. Confirm the preliminary find_pmd_or_thp_or_none() once page lock has been acquired and the page looks suitable: from then on its state is stable. However, collapse_pte_mapped_thp() was doing something others don't: freeing a page table still containing "valid" entries. i_mmap lock did stop a racing truncate from double-freeing those pages, but we prefer collapse_pte_mapped_thp() to clear the entries as usual. Their TLB flush can wait until the pmdp_collapse_flush() which follows, but the mmu_notifier_invalidate_range_start() has to be done earlier. Do the "step 1" checking loop without mmu_notifier: it wouldn't be good for khugepaged to keep on repeatedly invalidating a range which is then found unsuitable e.g. contains COWs. "step 2", which does the clearing, must then be more careful (after dropping ptl to do mmu_notifier), with abort prepared to correct the accounting like "step 3". But with those entries now cleared, "step 4" (after dropping ptl to do pmd_lock) is kept safe by the huge page lock, which stops new PTEs from being faulted in. [hughd@google.com: don't set mmap_locked = true in madvise_collapse()] Link: https://lkml.kernel.org/r/d3d9ff14-ef8-8f84-e160-bfa1f5794275@google.com [hughd@google.com: use ptep_clear() instead of pte_clear()] Link: https://lkml.kernel.org/r/e0197433-8a47-6a65-534d-eda26eeb78b0@google.com Link: https://lkml.kernel.org/r/b53be6a4-7715-51f9-aad-f1347dcb7c4@google.comSigned-off-by:
Qi Zheng <zhengqi.arch@bytedance.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Christoph Hellwig <hch@infradead.org> Cc: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Huang, Ying <ying.huang@intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Russell King <linux@armlinux.org.uk> Cc: SeongJae Park <sj@kernel.org> Cc: Song Liu <song@kernel.org> Cc: Steven Price <steven.price@arm.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Cc: Yang Shi <shy828301@gmail.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Zack Rusin <zackr@vmware.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by:
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Hugh Dickins authored
Simplify shmem and file THP collapse's retract_page_tables(), and relax its locking: to improve its success rate and to lessen impact on others. Instead of its MADV_COLLAPSE case doing set_huge_pmd() at target_addr of target_mm, leave that part of the work to madvise_collapse() calling collapse_pte_mapped_thp() afterwards: just adjust collapse_file()'s result code to arrange for that. That spares retract_page_tables() four arguments; and since it will be successful in retracting all of the page tables expected of it, no need to track and return a result code itself. It needs i_mmap_lock_read(mapping) for traversing the vma interval tree, but it does not need i_mmap_lock_write() for that: page_vma_mapped_walk() allows for pte_offset_map_lock() etc to fail, and uses pmd_lock() for THPs. retract_page_tables() just needs to use those same spinlocks to exclude it briefly, while transitioning pmd from page table to none: so restore its use of pmd_lock() inside of which pte lock is nested. Users of pte_offset_map_lock() etc all now allow for them to fail: so retract_page_tables() now has no use for mmap_write_trylock() or vma_try_start_write(). In common with rmap and page_vma_mapped_walk(), it does not even need the mmap_read_lock(). But those users do expect the page table to remain a good page table, until they unlock and rcu_read_unlock(): so the page table cannot be freed immediately, but rather by the recently added pte_free_defer(). Use the (usually a no-op) pmdp_get_lockless_sync() to send an interrupt when PAE, and pmdp_collapse_flush() did not already do so: to make sure that the start,pmdp_get_lockless(),end sequence in __pte_offset_map() cannot pick up a pmd entry with mismatched pmd_low and pmd_high. retract_page_tables() can be enhanced to replace_page_tables(), which inserts the final huge pmd without mmap lock: going through an invalid state instead of pmd_none() followed by fault. But that enhancement does raise some more questions: leave it until a later release. Link: https://lkml.kernel.org/r/f88970d9-d347-9762-ae6d-da978e8a4df@google.comSigned-off-by:
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Hugh Dickins authored
Add the generic pte_free_defer(), to call pte_free() via call_rcu(). pte_free_defer() will be called inside khugepaged's retract_page_tables() loop, where allocating extra memory cannot be relied upon. This version suits all those architectures which use an unfragmented page for one page table (none of whose pte_free()s use the mm arg which was passed to it). Link: https://lkml.kernel.org/r/78e921b0-b681-a1b0-dc20-44c9efa4ef3c@google.comSigned-off-by:
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Hugh Dickins authored
Add s390-specific pte_free_defer(), to free table page via call_rcu(). pte_free_defer() will be called inside khugepaged's retract_page_tables() loop, where allocating extra memory cannot be relied upon. This precedes the generic version to avoid build breakage from incompatible pgtable_t. This version is more complicated than others: because s390 fits two 2K page tables into one 4K page (so page->rcu_head must be shared between both halves), and already uses page->lru (which page->rcu_head overlays) to list any free halves; with clever management by page->_refcount bits. Build upon the existing management, adjusted to follow a new rule: that a page is never on the free list if pte_free_defer() was used on either half (marked by PageActive). And for simplicity, delay calling RCU until both halves are freed. Not adding back unallocated fragments to the list in pte_free_defer() can result in wasting some amount of memory for pagetables, depending on how long the allocated fragment will stay in use. In practice, this effect is expected to be insignificant, and not justify a far more complex approach, which might allow to add the fragments back later in __tlb_remove_table(), where we might not have a stable mm any more. [hughd@google.com: Claudio finds warning on mm_has_pgste() more useful than on mm_alloc_pgste()] Link: https://lkml.kernel.org/r/3bc095ba-a180-ce3b-82b1-2bfc64612f3@google.com Link: https://lkml.kernel.org/r/94eccf5f-264c-8abe-4567-e77f4b4e14a@google.comSigned-off-by:
Gerald Schaefer <gerald.schaefer@linux.ibm.com> Tested-by:
Alexander Gordeev <agordeev@linux.ibm.com> Acked-by:
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Hugh Dickins authored
Add sparc-specific pte_free_defer(), to call pte_free() via call_rcu(). pte_free_defer() will be called inside khugepaged's retract_page_tables() loop, where allocating extra memory cannot be relied upon. This precedes the generic version to avoid build breakage from incompatible pgtable_t. sparc32 supports pagetables sharing a page, but does not support THP; sparc64 supports THP, but does not support pagetables sharing a page. So the sparc-specific pte_free_defer() is as simple as the generic one, except for converting between pte_t *pgtable_t and struct page *. Link: https://lkml.kernel.org/r/dc4f318d-a66a-5622-dc44-9018ea814b37@google.comSigned-off-by:
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Hugh Dickins authored
Add powerpc-specific pte_free_defer(), to free table page via call_rcu(). pte_free_defer() will be called inside khugepaged's retract_page_tables() loop, where allocating extra memory cannot be relied upon. This precedes the generic version to avoid build breakage from incompatible pgtable_t. This is awkward because the struct page contains only one rcu_head, but that page may be shared between PTE_FRAG_NR pagetables, each wanting to use the rcu_head at the same time. But powerpc never reuses a fragment once it has been freed: so mark the page Active in pte_free_defer(), before calling pte_fragment_free() directly; and there call_rcu() to pte_free_now() when last fragment is freed and the page is PageActive. Link: https://lkml.kernel.org/r/6e3ca5f1-334d-4b14-b92d-fc8e99914fcb@google.comSuggested-by:
Jason Gunthorpe <jgg@ziepe.ca> Signed-off-by:
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Hugh Dickins authored
Instead of pte_lockptr(), use the recently added pte_offset_map_nolock() in assert_pte_locked(). BUG if pte_offset_map_nolock() fails. This mod might cause new crashes: which either expose my ignorance, or indicate issues to be fixed, or limit the usage of assert_pte_locked(). [hughd@google.com: assert_pte_locked() still needs the pmd_none() check] Link: https://lkml.kernel.org/r/c73d1543-532c-3da2-8cf2-a95363a14116@google.com Link: https://lkml.kernel.org/r/e8d56c95-c132-a82e-5f5f-7bb1b738b057@google.comSigned-off-by:
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Hugh Dickins authored
Instead of pte_lockptr(), use the recently added pte_offset_map_nolock() in adjust_pte(): because it gives the not-locked ptl for precisely that pte, which the caller can then safely lock; whereas pte_lockptr() is not so tightly coupled, because it dereferences the pmd pointer again. Link: https://lkml.kernel.org/r/4d5258bd-ffa0-018-253a-25f2c9b783f7@google.comSigned-off-by:
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Hugh Dickins authored
There is a faint risk that __pte_offset_map(), on a 32-bit architecture with a 64-bit pmd_t e.g. x86-32 with CONFIG_X86_PAE=y, would succeed on a pmdval assembled from a pmd_low and a pmd_high which never belonged together: their combination not pointing to a page table at all, perhaps not even a valid pfn. pmdp_get_lockless() is not enough to prevent that. Guard against that (on such configs) by local_irq_save() blocking TLB flush between present updates, as linux/pgtable.h suggests. It's only needed around the pmdp_get_lockless() in __pte_offset_map(): a race when __pte_offset_map_lock() repeats the pmdp_get_lockless() after getting the lock, would just send it back to __pte_offset_map() again. Complement this pmdp_get_lockless_start() and pmdp_get_lockless_end(), used only locally in __pte_offset_map(), with a pmdp_get_lockless_sync() synonym for tlb_remove_table_sync_one(): to send the necessary interrupt at the right moment on those configs which do not already send it. CONFIG_GUP_GET_PXX_LOW_HIGH is enabled when required by mips, sh and x86. It is not enabled by arm-32 CONFIG_ARM_LPAE: my understanding is that Will Deacon's 2020 enhancements to READ_ONCE() are sufficient for arm. It is not enabled by arc, but its pmd_t is 32-bit even when pte_t 64-bit. Limit the IRQ disablement to CONFIG_HIGHPTE? Perhaps, but would need a little more work, to retry if pmd_low good for page table, but pmd_high non-zero from THP (and that might be making x86-specific assumptions). Link: https://lkml.kernel.org/r/3adcd8f-9191-2df1-d7ea-c4877698aad@google.comSigned-off-by:
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Hugh Dickins authored
Patch series "mm: free retracted page table by RCU", v3. Some mmap_lock avoidance i.e. latency reduction. Initially just for the case of collapsing shmem or file pages to THPs: the usefulness of MADV_COLLAPSE on shmem is being limited by that mmap_write_lock it currently requires. Likely to be relied upon later in other contexts e.g. freeing of empty page tables (but that's not work I'm doing). mmap_write_lock avoidance when collapsing to anon THPs? Perhaps, but again that's not work I've done: a quick attempt was not as easy as the shmem/file case. These changes (though of course not these exact patches) have been in Google's data centre kernel for three years now: we do rely upon them. This patch (of 13): Before putting them to use (several commits later), add rcu_read_lock() to pte_offset_map(), and rcu_read_unlock() to pte_unmap(). Make this a separate commit, since it risks exposing imbalances: prior commits have fixed all the known imbalances, but we may find some have been missed. Link: https://lkml.kernel.org/r/7cd843a9-aa80-14f-5eb2-33427363c20@google.com Link: https://lkml.kernel.org/r/d3b01da5-2a6-833c-6681-67a3e024a16f@google.comSigned-off-by:
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Peng Zhang authored
The internal function mas_first_entry() is no longer used, so drop it. Link: https://lkml.kernel.org/r/20230711035444.526-9-zhangpeng.00@bytedance.comSigned-off-by:
Peng Zhang <zhangpeng.00@bytedance.com> Reviewed-by:
Liam R. Howlett <Liam.Howlett@oracle.com> Tested-by:
Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by:
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Peng Zhang authored
Replace mas_logical_pivot() with mas_safe_pivot() and drop mas_logical_pivot() since it won't be used anymore. We can do this since now all nodes will have node limit pivot (if it is not full node). Link: https://lkml.kernel.org/r/20230711035444.526-8-zhangpeng.00@bytedance.comSigned-off-by:
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Peng Zhang authored
Instead of using mas_first_entry() to find the leftmost leaf, use a simple loop instead. Remove an unneeded check for root node. To make the error message more accurate, check pivots first and then slots, because checking slots depend on the node limit pivot to break the loop. Link: https://lkml.kernel.org/r/20230711035444.526-7-zhangpeng.00@bytedance.comSigned-off-by:
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Peng Zhang authored
Update mas_validate_limits() to check root node, check node limit pivot if there is enough room for it to exist and check data_end. Remove the check for child existence as it is done in mas_validate_child_slot(). Link: https://lkml.kernel.org/r/20230711035444.526-6-zhangpeng.00@bytedance.comSigned-off-by:
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Peng Zhang authored
Don't break the loop before checking the last slot. Also here check if non-leaf nodes are missing children. Link: https://lkml.kernel.org/r/20230711035444.526-5-zhangpeng.00@bytedance.comSigned-off-by:
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