+ mm-page_alloc-remove-unused-fpi_flags-in-free_pages_prepare.patch added to mm-unstable branch

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

The patch titled
     Subject: mm/page_alloc: remove unused fpi_flags in free_pages_prepare()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-page_alloc-remove-unused-fpi_flags-in-free_pages_prepare.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-remove-unused-fpi_flags-in-free_pages_prepare.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: Zi Yan <ziy@nvidia.com>
Subject: mm/page_alloc: remove unused fpi_flags in free_pages_prepare()
Date: Fri, 16 Feb 2024 12:04:29 -0500

Patch series "Enable >0 order folio memory compaction", v6.

This patchset enables >0 order folio memory compaction, which is one of
the prerequisitions for large folio support[1].

I am aware of that split free pages is necessary for folio migration in
compaction, since if >0 order free pages are never split and no order-0
free page is scanned, compaction will end prematurely due to migration
returns -ENOMEM.  Free page split becomes a must instead of an
optimization.

lkp ncompare results (on a 8-CPU (Intel Xeon E5-2650 v4 @2.20GHz) 16G VM)
for default LRU (-no-mglru) and CONFIG_LRU_GEN are shown at the bottom,
copied from V3[4].

In sum, most of vm-scalability applications do not see performance change,
and the others see ~4% to ~26% performance boost under default LRU and ~2%
to ~6% performance boost under CONFIG_LRU_GEN.

To support >0 order folio compaction, the patchset changes how free pages used
for migration are kept during compaction. Free pages used to be split into
order-0 pages that are post allocation processed (i.e., PageBuddy flag cleared,
page order stored in page->private is zeroed, and page reference is set to 1).
Now all free pages are kept in a NR_PAGE_ORDER array of page lists based
on their order without post allocation process. When migrate_pages() asks for
a new page, one of the free pages, based on the requested page order, is
then processed and given out. And THP <2MB would need this feature.

[1] https://lore.kernel.org/linux-mm/f8d47176-03a8-99bf-a813-b5942830fd73@arm.com/
[2] https://lore.kernel.org/linux-mm/20231113170157.280181-1-zi.yan@sent.com/
[3] https://lore.kernel.org/linux-mm/20240123034636.1095672-1-zi.yan@sent.com/
[4] https://lore.kernel.org/linux-mm/20240202161554.565023-1-zi.yan@sent.com/
[5] https://lore.kernel.org/linux-mm/20240212163510.859822-1-zi.yan@sent.com/
[6] https://lore.kernel.org/linux-mm/20240214220420.1229173-1-zi.yan@sent.com/


This patch (of 4):

fpi_flags is only passed to should_skip_kasan_poison() but ignored by the
function.  Remove the unused parameter.

Link: https://lkml.kernel.org/r/20240216170432.1268753-2-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Adam Manzanares <a.manzanares@samsung.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_alloc.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/mm/page_alloc.c~mm-page_alloc-remove-unused-fpi_flags-in-free_pages_prepare
+++ a/mm/page_alloc.c
@@ -1061,7 +1061,7 @@ out:
  * on-demand allocation and then freed again before the deferred pages
  * initialization is done, but this is not likely to happen.
  */
-static inline bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
+static inline bool should_skip_kasan_poison(struct page *page)
 {
 	if (IS_ENABLED(CONFIG_KASAN_GENERIC))
 		return deferred_pages_enabled();
@@ -1081,10 +1081,10 @@ static void kernel_init_pages(struct pag
 }
 
 static __always_inline bool free_pages_prepare(struct page *page,
-			unsigned int order, fpi_t fpi_flags)
+			unsigned int order)
 {
 	int bad = 0;
-	bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags);
+	bool skip_kasan_poison = should_skip_kasan_poison(page);
 	bool init = want_init_on_free();
 	bool compound = PageCompound(page);
 
@@ -1266,7 +1266,7 @@ static void __free_pages_ok(struct page
 	unsigned long pfn = page_to_pfn(page);
 	struct zone *zone = page_zone(page);
 
-	if (!free_pages_prepare(page, order, fpi_flags))
+	if (!free_pages_prepare(page, order))
 		return;
 
 	/*
@@ -2343,7 +2343,7 @@ static bool free_unref_page_prepare(stru
 {
 	int migratetype;
 
-	if (!free_pages_prepare(page, order, FPI_NONE))
+	if (!free_pages_prepare(page, order))
 		return false;
 
 	migratetype = get_pfnblock_migratetype(page, pfn);
_

Patches currently in -mm which might be from ziy@nvidia.com are

mm-page_alloc-remove-unused-fpi_flags-in-free_pages_prepare.patch
mm-compaction-enable-compacting-0-order-folios.patch
mm-compaction-add-support-for-0-order-folio-memory-compaction.patch
mm-compaction-optimize-0-order-folio-compaction-with-free-page-split.patch