+ mempolicy-mpol_shared_policy_init-without-pseudo-vma.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mempolicy: mpol_shared_policy_init() without pseudo-vma
has been added to the -mm mm-unstable branch.  Its filename is
     mempolicy-mpol_shared_policy_init-without-pseudo-vma.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mempolicy-mpol_shared_policy_init-without-pseudo-vma.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Hugh Dickins <hughd@google.com>
Subject: mempolicy: mpol_shared_policy_init() without pseudo-vma
Date: Tue, 3 Oct 2023 02:22:59 -0700 (PDT)

mpol_shared_policy_init() does not need to use a pseudo-vma: it can use
sp_alloc() and sp_insert() directly, since the object's shared policy tree
is empty and inaccessible (needing no lock) at get_inode() time.

Link: https://lkml.kernel.org/r/3bef62d8-ae78-4c2-533-56a44ae425c@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun heo <tj@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mempolicy.c |   28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

--- a/mm/mempolicy.c~mempolicy-mpol_shared_policy_init-without-pseudo-vma
+++ a/mm/mempolicy.c
@@ -2756,30 +2756,30 @@ void mpol_shared_policy_init(struct shar
 	rwlock_init(&sp->lock);
 
 	if (mpol) {
-		struct vm_area_struct pvma;
-		struct mempolicy *new;
+		struct sp_node *sn;
+		struct mempolicy *npol;
 		NODEMASK_SCRATCH(scratch);
 
 		if (!scratch)
 			goto put_mpol;
-		/* contextualize the tmpfs mount point mempolicy */
-		new = mpol_new(mpol->mode, mpol->flags, &mpol->w.user_nodemask);
-		if (IS_ERR(new))
+
+		/* contextualize the tmpfs mount point mempolicy to this file */
+		npol = mpol_new(mpol->mode, mpol->flags, &mpol->w.user_nodemask);
+		if (IS_ERR(npol))
 			goto free_scratch; /* no valid nodemask intersection */
 
 		task_lock(current);
-		ret = mpol_set_nodemask(new, &mpol->w.user_nodemask, scratch);
+		ret = mpol_set_nodemask(npol, &mpol->w.user_nodemask, scratch);
 		task_unlock(current);
 		if (ret)
-			goto put_new;
-
-		/* Create pseudo-vma that contains just the policy */
-		vma_init(&pvma, NULL);
-		pvma.vm_end = TASK_SIZE;	/* policy covers entire file */
-		mpol_set_shared_policy(sp, &pvma, new); /* adds ref */
+			goto put_npol;
 
-put_new:
-		mpol_put(new);			/* drop initial ref */
+		/* alloc node covering entire file; adds ref to file's npol */
+		sn = sp_alloc(0, MAX_LFS_FILESIZE >> PAGE_SHIFT, npol);
+		if (sn)
+			sp_insert(sp, sn);
+put_npol:
+		mpol_put(npol);	/* drop initial ref on file's npol */
 free_scratch:
 		NODEMASK_SCRATCH_FREE(scratch);
 put_mpol:
_

Patches currently in -mm which might be from hughd@google.com are

shmem-shrink-shmem_inode_info-dir_offsets-in-a-union.patch
shmem-remove-vma-arg-from-shmem_get_folio_gfp.patch
shmem-factor-shmem_falloc_wait-out-of-shmem_fault.patch
shmem-trivial-tidyups-removing-extra-blank-lines-etc.patch
shmem-shmem_acct_blocks-and-shmem_inode_acct_blocks.patch
shmem-move-memcg-charge-out-of-shmem_add_to_page_cache.patch
shmem-_add_to_page_cache-before-shmem_inode_acct_blocks.patch
shmempercpu_counter-add-_limited_addfbc-limit-amount.patch
hugetlbfs-drop-shared-numa-mempolicy-pretence.patch
kernfs-drop-shared-numa-mempolicy-hooks.patch
mempolicy-fix-migrate_pages2-syscall-return-nr_failed.patch
mempolicy-trivia-delete-those-ancient-pr_debugs.patch
mempolicy-trivia-slightly-more-consistent-naming.patch
mempolicy-trivia-use-pgoff_t-in-shared-mempolicy-tree.patch
mempolicy-mpol_shared_policy_init-without-pseudo-vma.patch
mempolicy-remove-confusing-mpol_mf_lazy-dead-code.patch
mm-add-page_rmappable_folio-wrapper.patch
mempolicy-alloc_pages_mpol-for-numa-policy-without-vma.patch
mempolicy-mmap_lock-is-not-needed-while-migrating-folios.patch
mempolicy-migration-attempt-to-match-interleave-nodes.patch