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authorHugh Dickins <hughd@google.com>2022-02-14 18:26:39 -0800
committerMatthew Wilcox (Oracle) <willy@infradead.org>2022-02-17 11:56:48 -0500
commitcea86fe246b694a191804b47378eb9d77aefabec (patch)
tree718e26877387eb07d276fab1f607f519a2987795 /mm/ksm.c
parenta213e5cf71cbcea4b23caedcb8fe6629a333b275 (diff)
mm/munlock: rmap call mlock_vma_page() munlock_vma_page()
Add vma argument to mlock_vma_page() and munlock_vma_page(), make them inline functions which check (vma->vm_flags & VM_LOCKED) before calling mlock_page() and munlock_page() in mm/mlock.c. Add bool compound to mlock_vma_page() and munlock_vma_page(): this is because we have understandable difficulty in accounting pte maps of THPs, and if passed a PageHead page, mlock_page() and munlock_page() cannot tell whether it's a pmd map to be counted or a pte map to be ignored. Add vma arg to page_add_file_rmap() and page_remove_rmap(), like the others, and use that to call mlock_vma_page() at the end of the page adds, and munlock_vma_page() at the end of page_remove_rmap() (end or beginning? unimportant, but end was easier for assertions in testing). No page lock is required (although almost all adds happen to hold it): delete the "Serialize with page migration" BUG_ON(!PageLocked(page))s. Certainly page lock did serialize with page migration, but I'm having difficulty explaining why that was ever important. Mlock accounting on THPs has been hard to define, differed between anon and file, involved PageDoubleMap in some places and not others, required clear_page_mlock() at some points. Keep it simple now: just count the pmds and ignore the ptes, there is no reason for ptes to undo pmd mlocks. page_add_new_anon_rmap() callers unchanged: they have long been calling lru_cache_add_inactive_or_unevictable(), which does its own VM_LOCKED handling (it also checks for not VM_SPECIAL: I think that's overcautious, and inconsistent with other checks, that mmap_region() already prevents VM_LOCKED on VM_SPECIAL; but haven't quite convinced myself to change it). Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Diffstat (limited to 'mm/ksm.c')
-rw-r--r--mm/ksm.c12
1 files changed, 1 insertions, 11 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index c20bd4d9a0d9..c5a4403b5dc9 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1177,7 +1177,7 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
ptep_clear_flush(vma, addr, ptep);
set_pte_at_notify(mm, addr, ptep, newpte);
- page_remove_rmap(page, false);
+ page_remove_rmap(page, vma, false);
if (!page_mapped(page))
try_to_free_swap(page);
put_page(page);
@@ -1252,16 +1252,6 @@ static int try_to_merge_one_page(struct vm_area_struct *vma,
err = replace_page(vma, page, kpage, orig_pte);
}
- if ((vma->vm_flags & VM_LOCKED) && kpage && !err) {
- munlock_vma_page(page);
- if (!PageMlocked(kpage)) {
- unlock_page(page);
- lock_page(kpage);
- mlock_vma_page(kpage);
- page = kpage; /* for final unlock */
- }
- }
-
out_unlock:
unlock_page(page);
out: