The patch titled
Subject: mm/gup: remove FOLL_MIGRATION
has been added to the -mm mm-unstable branch. Its filename is
mm-gup-remove-foll_migration.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-gup-remove-foll_migration.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: David Hildenbrand <david@xxxxxxxxxx>
Subject: mm/gup: remove FOLL_MIGRATION
Date: Fri, 21 Oct 2022 12:11:41 +0200
Fortunately, the last user (KSM) is gone, so let's just remove this rather
special code from generic GUP handling -- especially because KSM never
required the PMD handling as KSM only deals with individual base pages.
Link: https://lkml.kernel.org/r/20221021101141.84170-10-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 1 -
mm/gup.c | 31 +++----------------------------
2 files changed, 3 insertions(+), 29 deletions(-)
--- a/include/linux/mm.h~mm-gup-remove-foll_migration
+++ a/include/linux/mm.h
@@ -2920,7 +2920,6 @@ struct page *follow_page(struct vm_area_
* and return without waiting upon it */
#define FOLL_NOFAULT 0x80 /* do not fault in pages */
#define FOLL_HWPOISON 0x100 /* check page is hwpoisoned */
-#define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */
#define FOLL_TRIED 0x800 /* a retry, previous pass started an IO */
#define FOLL_REMOTE 0x2000 /* we are working on non-current tsk/mm */
#define FOLL_ANON 0x8000 /* don't do file mappings */
--- a/mm/gup.c~mm-gup-remove-foll_migration
+++ a/mm/gup.c
@@ -533,30 +533,13 @@ static struct page *follow_page_pte(stru
if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
(FOLL_PIN | FOLL_GET)))
return ERR_PTR(-EINVAL);
-retry:
if (unlikely(pmd_bad(*pmd)))
return no_page_table(vma, flags);
ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
pte = *ptep;
- if (!pte_present(pte)) {
- swp_entry_t entry;
- /*
- * KSM's break_ksm() relies upon recognizing a ksm page
- * even while it is being migrated, so for that case we
- * need migration_entry_wait().
- */
- if (likely(!(flags & FOLL_MIGRATION)))
- goto no_page;
- if (pte_none(pte))
- goto no_page;
- entry = pte_to_swp_entry(pte);
- if (!is_migration_entry(entry))
- goto no_page;
- pte_unmap_unlock(ptep, ptl);
- migration_entry_wait(mm, pmd, address);
- goto retry;
- }
+ if (!pte_present(pte))
+ goto no_page;
if (pte_protnone(pte) && !gup_can_follow_protnone(flags))
goto no_page;
@@ -688,18 +671,10 @@ retry:
if (pmd_protnone(pmdval) && !gup_can_follow_protnone(flags))
return no_page_table(vma, flags);
-retry_locked:
ptl = pmd_lock(mm, pmd);
- if (unlikely(pmd_none(*pmd))) {
- spin_unlock(ptl);
- return no_page_table(vma, flags);
- }
if (unlikely(!pmd_present(*pmd))) {
spin_unlock(ptl);
- if (likely(!(flags & FOLL_MIGRATION)))
- return no_page_table(vma, flags);
- pmd_migration_entry_wait(mm, pmd);
- goto retry_locked;
+ return no_page_table(vma, flags);
}
if (unlikely(!(pmd_trans_huge(*pmd) || pmd_devmap(pmdval)))) {
spin_unlock(ptl);
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
selftests-vm-anon_cow-test-cow-handling-of-anonymous-memory.patch
selftests-vm-factor-out-pagemap_is_populated-into-vm_util.patch
selftests-vm-anon_cow-thp-tests.patch
selftests-vm-anon_cow-hugetlb-tests.patch
selftests-vm-anon_cow-add-liburing-test-cases.patch
mm-gup_test-start-stop-read-functionality-for-pin-longterm-test.patch
mm-gup_test-start-stop-read-functionality-for-pin-longterm-test-fix.patch
selftests-vm-anon_cow-add-r-o-longterm-tests-via-gup_test.patch
selftests-vm-add-ksm-unmerge-tests.patch
mm-pagewalk-dont-trigger-test_walk-in-walk_page_vma.patch
selftests-vm-add-test-to-measure-madv_unmergeable-performance.patch
mm-ksm-simplify-break_ksm-to-not-rely-on-vm_fault_write.patch
mm-remove-vm_fault_write.patch
mm-ksm-fix-ksm-cow-breaking-with-userfaultfd-wp-via-fault_flag_unshare.patch
mm-pagewalk-add-walk_page_range_vma.patch
mm-ksm-convert-break_ksm-to-use-walk_page_range_vma.patch
mm-gup-remove-foll_migration.patch
