The patch titled
Subject: mm/migration: reduce the rcu lock duration
has been added to the -mm tree. Its filename is
mm-migration-reduce-the-rcu-lock-duration.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-migration-reduce-the-rcu-lock-duration.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-migration-reduce-the-rcu-lock-duration.patch
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------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm/migration: reduce the rcu lock duration
Patch series "A few cleanup and fixup patches for migration", v2.
This series contains a few patches to remove unneeded lock page and
PageMovable check, reduce the rcu lock duration. Also we fix potential
pte_unmap on an not mapped pte. More details can be found in the
respective changelogs.
This patch (of 4):
rcu_read_lock is required by grabbing the task refcount but it's not
needed for ptrace_may_access. So we could release the rcu lock after task
refcount is successfully grabbed to reduce the rcu holding time.
Link: https://lkml.kernel.org/r/20220425132723.34824-1-linmiaohe@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20220425132723.34824-2-linmiaohe@xxxxxxxxxx
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/mm/migrate.c~mm-migration-reduce-the-rcu-lock-duration
+++ a/mm/migrate.c
@@ -1902,17 +1902,16 @@ static struct mm_struct *find_mm_struct(
return ERR_PTR(-ESRCH);
}
get_task_struct(task);
+ rcu_read_unlock();
/*
* Check if this process has the right to modify the specified
* process. Use the regular "ptrace_may_access()" checks.
*/
if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
- rcu_read_unlock();
mm = ERR_PTR(-EPERM);
goto out;
}
- rcu_read_unlock();
mm = ERR_PTR(security_task_movememory(task));
if (IS_ERR(mm))
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
mm-shmem-make-shmem_init-return-void.patch
mm-memcg-remove-unneeded-nr_scanned.patch
mm-mmapc-use-helper-mlock_future_check.patch
mm-mremap-use-helper-mlock_future_check.patch
mm-mremap-avoid-unneeded-do_munmap-call.patch
mm-memory-failurec-minor-cleanup-for-hwpoisonhandlable.patch
mm-memory-failurec-dissolve-truncated-hugetlb-page.patch
mm-vmscan-remove-obsolete-comment-in-get_scan_count.patch
mm-vmscan-fix-comment-for-current_may_throttle.patch
mm-vmscan-fix-comment-for-isolate_lru_pages.patch
mm-z3fold-declare-z3fold_mount-with-__init.patch
mm-z3fold-remove-obsolete-comment-in-z3fold_alloc.patch
mm-z3fold-minor-clean-up-for-z3fold_free.patch
mm-z3fold-remove-unneeded-page_mapcount_reset-and-clearpageprivate.patch
mm-z3fold-remove-confusing-local-variable-l-reassignment.patch
mm-z3fold-move-decrement-of-pool-pages_nr-into-__release_z3fold_page.patch
mm-z3fold-remove-redundant-list_del_init-of-zhdr-buddy-in-z3fold_free.patch
mm-z3fold-remove-unneeded-page_headless-check-in-free_handle.patch
mm-compaction-use-helper-isolation_suitable.patch
drivers-base-nodec-fix-compaction-sysfs-file-leak.patch
mm-mempolicy-clean-up-the-code-logic-in-queue_pages_pte_range.patch
mm-migration-remove-unneeded-local-variable-mapping_locked.patch
mm-migration-remove-unneeded-local-variable-page_lru.patch
mm-migration-use-helper-function-vma_lookup-in-add_page_for_migration.patch
mm-migration-use-helper-macro-min-in-do_pages_stat.patch
mm-migration-avoid-unneeded-nodemask_t-initialization.patch
mm-migration-remove-some-duplicated-codes-in-migrate_pages.patch
mm-migration-fix-potential-page-refcounts-leak-in-migrate_pages.patch
mm-migration-fix-potential-invalid-node-access-for-reclaim-based-migration.patch
mm-migration-fix-possible-do_pages_stat_array-racing-with-memory-offline.patch
mm-madvise-fix-potential-pte_unmap_unlock-pte-error.patch
mm-madvise-free-hwpoison-and-swapin-error-entry-in-madvise_free_pte_range.patch
mm-compaction-remove-unneeded-return-value-of-kcompactd_run.patch
mm-compaction-remove-unneeded-pfn-update.patch
mm-compaction-remove-unneeded-assignment-to-isolate_start_pfn.patch
mm-compaction-clean-up-comment-for-sched-contention.patch
mm-compaction-clean-up-comment-about-suitable-migration-target-recheck.patch
mm-compaction-use-compact_cluster_max-in-compactionc.patch
mm-compaction-use-helper-compound_nr-in-isolate_migratepages_block.patch
mm-compaction-clean-up-comment-about-async-compaction-in-isolate_migratepages.patch
mm-compaction-avoid-possible-null-pointer-dereference-in-kcompactd_cpu_online.patch
mm-compaction-make-compaction_zonelist_suitable-return-false-when-compact_success.patch
mm-compaction-simplify-the-code-in-__compact_finished.patch
mm-compaction-make-sure-highest-is-above-the-min_pfn.patch
mm-swapfile-unuse_pte-can-map-random-data-if-swap-read-fails.patch
mm-swapfile-fix-lost-swap-bits-in-unuse_pte.patch
mm-migration-reduce-the-rcu-lock-duration.patch
mm-migration-remove-unneeded-lock-page-and-pagemovable-check.patch
mm-migration-return-errno-when-isolate_huge_page-failed.patch
mm-migration-fix-potential-pte_unmap-on-an-not-mapped-pte.patch
