+ mm-gup-remove-gup_fast_pgd_leaf-and-clean-up-the-relevant-codes.patch added to mm-new branch

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

The patch titled
     Subject: mm/gup: remove gup_fast_pgd_leaf() and clean up the relevant codes
has been added to the -mm mm-new branch.  Its filename is
     mm-gup-remove-gup_fast_pgd_leaf-and-clean-up-the-relevant-codes.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-gup_fast_pgd_leaf-and-clean-up-the-relevant-codes.patch

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

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------------------------------------------------------
From: Baoquan He <bhe@redhat.com>
Subject: mm/gup: remove gup_fast_pgd_leaf() and clean up the relevant codes
Date: Mon, 31 Mar 2025 16:13:24 +0800

In the current kernel, only pud huge page is supported in some
architectures.  P4d and pgd huge pages haven't been supported yet.  And in
mm/gup.c, there's no pgd huge page handling in the follow_page_mask() code
path.  Hence it doesn't make sense to have gup_fast_pgd_leaf() in gup_fast
code path.

Here remove gup_fast_pgd_leaf() and clean up the relevant codes.

Link: https://lkml.kernel.org/r/20250331081327.256412-5-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: <x86@kernel.org>
Cc: Yanjun.Zhu <yanjun.zhu@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/gup.c |   49 +++----------------------------------------------
 1 file changed, 3 insertions(+), 46 deletions(-)

--- a/mm/gup.c~mm-gup-remove-gup_fast_pgd_leaf-and-clean-up-the-relevant-codes
+++ a/mm/gup.c
@@ -3163,46 +3163,6 @@ static int gup_fast_pud_leaf(pud_t orig,
 	return 1;
 }
 
-static int gup_fast_pgd_leaf(pgd_t orig, pgd_t *pgdp, unsigned long addr,
-		unsigned long end, unsigned int flags, struct page **pages,
-		int *nr)
-{
-	int refs;
-	struct page *page;
-	struct folio *folio;
-
-	if (!pgd_access_permitted(orig, flags & FOLL_WRITE))
-		return 0;
-
-	BUILD_BUG_ON(pgd_devmap(orig));
-
-	page = pgd_page(orig);
-	refs = record_subpages(page, PGDIR_SIZE, addr, end, pages + *nr);
-
-	folio = try_grab_folio_fast(page, refs, flags);
-	if (!folio)
-		return 0;
-
-	if (unlikely(pgd_val(orig) != pgd_val(*pgdp))) {
-		gup_put_folio(folio, refs, flags);
-		return 0;
-	}
-
-	if (!pgd_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) {
-		gup_put_folio(folio, refs, flags);
-		return 0;
-	}
-
-	if (!gup_fast_folio_allowed(folio, flags)) {
-		gup_put_folio(folio, refs, flags);
-		return 0;
-	}
-
-	*nr += refs;
-	folio_set_referenced(folio);
-	return 1;
-}
-
 static int gup_fast_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr,
 		unsigned long end, unsigned int flags, struct page **pages,
 		int *nr)
@@ -3297,12 +3257,9 @@ static void gup_fast_pgd_range(unsigned
 		next = pgd_addr_end(addr, end);
 		if (pgd_none(pgd))
 			return;
-		if (unlikely(pgd_leaf(pgd))) {
-			if (!gup_fast_pgd_leaf(pgd, pgdp, addr, next, flags,
-					       pages, nr))
-				return;
-		} else if (!gup_fast_p4d_range(pgdp, pgd, addr, next, flags,
-					       pages, nr))
+		BUILD_BUG_ON(pgd_leaf(pgd));
+		if (!gup_fast_p4d_range(pgdp, pgd, addr, next, flags,
+					pages, nr))
 			return;
 	} while (pgdp++, addr = next, addr != end);
 }
_

Patches currently in -mm which might be from bhe@redhat.com are

mm-gup-fix-wrongly-calculated-returned-value-in-fault_in_safe_writeable.patch
mm-gup-check-if-both-gup_get-and-gup_pin-are-set-in-__get_user_pages-earlier.patch
mm-gup-fix-the-outdated-code-comments-above-get_user_pages_unlocked.patch
mm-gup-remove-gup_fast_pgd_leaf-and-clean-up-the-relevant-codes.patch
x86-mm-remove-pgd_leaf-definition-in-arch.patch
x86-mm-remove-p4d_leaf-definition.patch
mm-pgtable-remove-unneeded-pgd_devmap.patch