+ fs-proc-page-respect-folio-head-page-flag-placement.patch added to mm-unstable branch

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

The patch titled
     Subject: fs/proc/page: respect folio head-page flag placement
has been added to the -mm mm-unstable branch.  Its filename is
     fs-proc-page-respect-folio-head-page-flag-placement.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fs-proc-page-respect-folio-head-page-flag-placement.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: Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: fs/proc/page: respect folio head-page flag placement
Date: Fri, 10 Nov 2023 11:33:20 +0800

kpageflags reads page-flags directly from the page, even when the
respective flag is only updated on the headpage of a folio.

Since most flags are stored in head flags, make k = folio->flags, and add
new p = page->flags used for per-page flags.

Based upon a patch by Gregory Price.

Link: https://lkml.kernel.org/r/20231110033324.2455523-4-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Cc: Gregory Price <gregory.price@memverge.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/proc/page.c |   18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

--- a/fs/proc/page.c~fs-proc-page-respect-folio-head-page-flag-placement
+++ a/fs/proc/page.c
@@ -110,8 +110,7 @@ static inline u64 kpf_copy_bit(u64 kflag
 u64 stable_page_flags(struct page *page)
 {
 	struct folio *folio;
-	u64 k;
-	u64 u;
+	u64 k, p, u;
 
 	/*
 	 * pseudo flag: KPF_NOPAGE
@@ -121,7 +120,8 @@ u64 stable_page_flags(struct page *page)
 		return 1 << KPF_NOPAGE;
 
 	folio = page_folio(page);
-	k = page->flags;
+	k = folio->flags;
+	p = page->flags;
 	u = 0;
 
 	/*
@@ -202,7 +202,7 @@ u64 stable_page_flags(struct page *page)
 	u |= kpf_copy_bit(k, KPF_MLOCKED,	PG_mlocked);
 
 #ifdef CONFIG_MEMORY_FAILURE
-	u |= kpf_copy_bit(k, KPF_HWPOISON,	PG_hwpoison);
+	u |= kpf_copy_bit(p, KPF_HWPOISON,	PG_hwpoison);
 #endif
 
 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
@@ -211,13 +211,13 @@ u64 stable_page_flags(struct page *page)
 
 	u |= kpf_copy_bit(k, KPF_RESERVED,	PG_reserved);
 	u |= kpf_copy_bit(k, KPF_MAPPEDTODISK,	PG_mappedtodisk);
-	u |= kpf_copy_bit(k, KPF_PRIVATE,	PG_private);
-	u |= kpf_copy_bit(k, KPF_PRIVATE_2,	PG_private_2);
-	u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE,	PG_owner_priv_1);
+	u |= kpf_copy_bit(p, KPF_PRIVATE,	PG_private);
+	u |= kpf_copy_bit(p, KPF_PRIVATE_2,	PG_private_2);
+	u |= kpf_copy_bit(p, KPF_OWNER_PRIVATE,	PG_owner_priv_1);
 	u |= kpf_copy_bit(k, KPF_ARCH,		PG_arch_1);
 #ifdef CONFIG_ARCH_USES_PG_ARCH_X
-	u |= kpf_copy_bit(k, KPF_ARCH_2,	PG_arch_2);
-	u |= kpf_copy_bit(k, KPF_ARCH_3,	PG_arch_3);
+	u |= kpf_copy_bit(p, KPF_ARCH_2,	PG_arch_2);
+	u |= kpf_copy_bit(p, KPF_ARCH_3,	PG_arch_3);
 #endif
 
 	return u;
_

Patches currently in -mm which might be from wangkefeng.wang@huawei.com are

fs-proc-page-remove-unneeded-pagetail-pageslab-check.patch
fs-proc-page-use-a-folio-in-stable_page_flags.patch
fs-proc-page-respect-folio-head-page-flag-placement.patch
mm-huge_memory-use-more-folio-api-in-__split_huge_page_tail.patch
mm-task_mmu-use-a-folio-in-smaps_account.patch
mm-task_mmu-use-a-folio-in-clear_refs_pte_range.patch
page_idle-kill-page-idle-and-young-wrapper.patch