From: David Hildenbrand <david@redhat.com>
Date: Fri, 2 Aug 2024 15:55:20 +0000 (+0200)
Subject: mm/huge_memory: convert split_huge_pages_pid() from follow_page() to folio_walk
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=61628fc480eca1cad0ff01339b58103b9280b435;p=users%2Fjedix%2Flinux-maple.git

mm/huge_memory: convert split_huge_pages_pid() from follow_page() to folio_walk

Let's remove yet another follow_page() user.  Note that we have to do the
split without holding the PTL, after folio_walk_end().  We don't care
about losing the secretmem check in follow_page().

Link: https://lkml.kernel.org/r/20240802155524.517137-8-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 29e76d285e4b5..fe4f8415edfd2 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -40,6 +40,7 @@
 #include <linux/memory-tiers.h>
 #include <linux/compat.h>
 #include <linux/pgalloc_tag.h>
+#include <linux/pagewalk.h>
 
 #include <asm/tlb.h>
 #include <asm/pgalloc.h>
@@ -3504,7 +3505,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
 	 */
 	for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) {
 		struct vm_area_struct *vma = vma_lookup(mm, addr);
-		struct page *page;
+		struct folio_walk fw;
 		struct folio *folio;
 
 		if (!vma)
@@ -3516,13 +3517,10 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
 			continue;
 		}
 
-		/* FOLL_DUMP to ignore special (like zero) pages */
-		page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
-
-		if (IS_ERR_OR_NULL(page))
+		folio = folio_walk_start(&fw, vma, addr, 0);
+		if (!folio)
 			continue;
 
-		folio = page_folio(page);
 		if (!is_transparent_hugepage(folio))
 			goto next;
 
@@ -3541,13 +3539,19 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
 
 		if (!folio_trylock(folio))
 			goto next;
+		folio_get(folio);
+		folio_walk_end(&fw, vma);
 
 		if (!split_folio_to_order(folio, new_order))
 			split++;
 
 		folio_unlock(folio);
-next:
 		folio_put(folio);
+
+		cond_resched();
+		continue;
+next:
+		folio_walk_end(&fw, vma);
 		cond_resched();
 	}
 	mmap_read_unlock(mm);