The patch titled
Subject: mm: respect mmap hint before THP alignment if allocation is possible
has been added to the -mm mm-unstable branch. Its filename is
mm-respect-mmap-hint-before-thp-alignment-if-allocation-is-possible.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-respect-mmap-hint-before-thp-alignment-if-allocation-is-possible.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: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
Subject: mm: respect mmap hint before THP alignment if allocation is possible
Date: Wed, 11 Dec 2024 15:27:54 -0800
Commit 249608ee4713 ("mm: respect mmap hint address when aligning for
THP") fallsback to PAGE_SIZE alignment instead of THP alignment for
anonymous mapping as long as a hint address is provided by the user --
even if we weren't able to allocate the unmapped area at the hint address
in the end.
This was done to address the immediate regression in anonymous mappings
where the hint address were being ignored in some cases; due to commit
efa7df3e3bb5 ("mm: align larger anonymous mappings on THP boundaries").
It was later pointed out that this issue also existed for file-backed
mappings from file systems that use thp_get_unmapped_area() for their
.get_unmapped_area() file operation.
The same fix was not applied for file-backed mappings since it would mean
any mmap requests that provide a hint address would be only
PAGE_SIZE-aligned regardless of whether allocation was successful at the
hint address or not.
Instead, use arch_mmap_hint() to first attempt allocation at the hint
address and fallback to THP alignment if there isn't sufficient VA space
to satisfy the allocation at the hint address.
Link: https://lkml.kernel.org/r/20241211232754.1583023-17-kaleshsingh@xxxxxxxxxx
Signed-off-by: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
Cc: Andreas Larsson <andreas@xxxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Cc: Breno Leitao <leitao@xxxxxxxxxx>
Cc: Chris Zankel <chris@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Cc: Jason Andryuk <jason.andryuk@xxxxxxx>
Cc: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Rich Felker <dalias@xxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Yang Shi <yang@xxxxxxxxxxxxxxxxxxxxxx>
Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 17 ++++++++++-------
mm/mmap.c | 1 -
2 files changed, 10 insertions(+), 8 deletions(-)
--- a/mm/huge_memory.c~mm-respect-mmap-hint-before-thp-alignment-if-allocation-is-possible
+++ a/mm/huge_memory.c
@@ -1097,6 +1097,16 @@ static unsigned long __thp_get_unmapped_
loff_t off_align = round_up(off, size);
unsigned long len_pad, ret, off_sub;
+ /*
+ * If allocation at the address hint succeeds; respect the hint and
+ * don't try to align to THP boundary;
+ *
+ * Or if an the requested extent is invalid return the error immediately.
+ */
+ addr = arch_mmap_hint(filp, addr, len, off, flags);
+ if (addr)
+ return addr;
+
if (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall())
return 0;
@@ -1117,13 +1127,6 @@ static unsigned long __thp_get_unmapped_
if (IS_ERR_VALUE(ret))
return 0;
- /*
- * Do not try to align to THP boundary if allocation at the address
- * hint succeeds.
- */
- if (ret == addr)
- return addr;
-
off_sub = (off - ret) & (size - 1);
if (test_bit(MMF_TOPDOWN, ¤t->mm->flags) && !off_sub)
--- a/mm/mmap.c~mm-respect-mmap-hint-before-thp-alignment-if-allocation-is-possible
+++ a/mm/mmap.c
@@ -814,7 +814,6 @@ __get_unmapped_area(struct file *file, u
if (get_area) {
addr = get_area(file, addr, len, pgoff, flags);
} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && !file
- && !addr /* no hint */
&& IS_ALIGNED(len, PMD_SIZE)) {
/* Ensures that larger anonymous mappings are THP aligned. */
addr = thp_get_unmapped_area_vmflags(file, addr, len,
_
Patches currently in -mm which might be from kaleshsingh@xxxxxxxxxx are
mm-introduce-generic_mmap_hint.patch
mm-x86-introduce-arch_mmap_hint.patch
mm-arm-introduce-arch_mmap_hint.patch
mm-alpha-introduce-arch_mmap_hint.patch
mm-arc-use-generic_mmap_hint.patch
mm-csky-introduce-arch_mmap_hint.patch
mm-loongarch-introduce-arch_mmap_hint.patch
mm-mips-introduce-arch_align_mmap_hint.patch
mm-parisc-introduce-arch_align_mmap_hint.patch
mm-s390-use-generic_mmap_hint.patch
mm-sh-introduce-arch_mmap_hint.patch
mm-sparc32-introduce-arch_mmap_hint.patch
mm-sparc64-introduce-arch_mmap_hint.patch
mm-xtensa-introduce-arch_mmap_hint.patch
mm-powerpc-introduce-arch_mmap_hint.patch
mm-respect-mmap-hint-before-thp-alignment-if-allocation-is-possible.patch
