The patch titled
Subject: mm: introduce folio_is_pfmemalloc
has been added to the -mm mm-unstable branch. Its filename is
mm-introduce-folio_is_pfmemalloc.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-introduce-folio_is_pfmemalloc.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: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
Subject: mm: introduce folio_is_pfmemalloc
Date: Fri, 6 Jan 2023 15:52:51 -0600
Add a folio equivalent for page_is_pfmemalloc. This removes two instances
of page_is_pfmemalloc(folio_page(folio, 0)) so the folio can be used
directly.
Link: https://lkml.kernel.org/r/20230106215251.599222-1-sidhartha.kumar@xxxxxxxxxx
Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: SeongJae Park <sj@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 15 +++++++++++++++
mm/slab.c | 2 +-
mm/slub.c | 2 +-
3 files changed, 17 insertions(+), 2 deletions(-)
--- a/include/linux/mm.h~mm-introduce-folio_is_pfmemalloc
+++ a/include/linux/mm.h
@@ -1965,6 +1965,21 @@ static inline bool page_is_pfmemalloc(co
}
/*
+ * Return true only if the folio has been allocated with
+ * ALLOC_NO_WATERMARKS and the low watermark was not
+ * met implying that the system is under some pressure.
+ */
+static inline bool folio_is_pfmemalloc(const struct folio *folio)
+{
+ /*
+ * lru.next has bit 1 set if the page is allocated from the
+ * pfmemalloc reserves. Callers may simply overwrite it if
+ * they do not need to preserve that information.
+ */
+ return (uintptr_t)folio->lru.next & BIT(1);
+}
+
+/*
* Only to be called by the page allocator on a freshly allocated
* page.
*/
--- a/mm/slab.c~mm-introduce-folio_is_pfmemalloc
+++ a/mm/slab.c
@@ -1373,7 +1373,7 @@ static struct slab *kmem_getpages(struct
/* Make the flag visible before any changes to folio->mapping */
smp_wmb();
/* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */
- if (sk_memalloc_socks() && page_is_pfmemalloc(folio_page(folio, 0)))
+ if (sk_memalloc_socks() && folio_is_pfmemalloc(folio))
slab_set_pfmemalloc(slab);
return slab;
--- a/mm/slub.c~mm-introduce-folio_is_pfmemalloc
+++ a/mm/slub.c
@@ -1859,7 +1859,7 @@ static inline struct slab *alloc_slab_pa
__folio_set_slab(folio);
/* Make the flag visible before any changes to folio->mapping */
smp_wmb();
- if (page_is_pfmemalloc(folio_page(folio, 0)))
+ if (folio_is_pfmemalloc(folio))
slab_set_pfmemalloc(slab);
return slab;
_
Patches currently in -mm which might be from sidhartha.kumar@xxxxxxxxxx are
mm-move-folio_set_compound_order-to-mm-internalh.patch
mm-introduce-folio_is_pfmemalloc.patch
