+ mm-introduce-generic_mmap_hint.patch added to mm-unstable branch

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

The patch titled
     Subject: mm: introduce generic_mmap_hint()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-introduce-generic_mmap_hint.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-introduce-generic_mmap_hint.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@google.com>
Subject: mm: introduce generic_mmap_hint()
Date: Wed, 11 Dec 2024 15:27:39 -0800

Patch series "mm: Introduce arch_mmap_hint()", v2.

This series introduces arch_mmap_hint() to handle allocating VA space
for the hint address.

Patches 1-16 introduce this new helper and Patch 17 uses it to fix the
issue of mmap hint being ignored in some cases due to THP alignment [1]

[1] https://lore.kernel.org/r/20241118214650.3667577-1-kaleshsingh@google.com/


This patch (of 16):

Consolidate the hint searches from both directions (topdown and bottomup)
into generic_mmap_hint().

No functional change is introduced.

Link: https://lkml.kernel.org/r/20241211232754.1583023-1-kaleshsingh@google.com
Link: https://lkml.kernel.org/r/20241211232754.1583023-2-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Breno Leitao <leitao@debian.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jason Andryuk <jason.andryuk@amd.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/sched/mm.h |    4 +
 mm/mmap.c                |   76 ++++++++++++++++++++++---------------
 2 files changed, 50 insertions(+), 30 deletions(-)

--- a/include/linux/sched/mm.h~mm-introduce-generic_mmap_hint
+++ a/include/linux/sched/mm.h
@@ -201,6 +201,10 @@ unsigned long mm_get_unmapped_area_vmfla
 					   unsigned long flags,
 					   vm_flags_t vm_flags);
 
+unsigned long generic_mmap_hint(struct file *filp, unsigned long addr,
+				unsigned long len, unsigned long pgoff,
+				unsigned long flags);
+
 unsigned long
 generic_get_unmapped_area(struct file *filp, unsigned long addr,
 			  unsigned long len, unsigned long pgoff,
--- a/mm/mmap.c~mm-introduce-generic_mmap_hint
+++ a/mm/mmap.c
@@ -620,6 +620,47 @@ unsigned long vm_unmapped_area(struct vm
 	return addr;
 }
 
+/*
+ * Look up unmapped area at the requested hint addr
+ *
+ * NOTE: MAP_FIXED is also handled here since it's a special case of
+ * enforcing the hint address.
+ *
+ * Returns:
+ *    ERR_VALUE: If the requested mapping is not valid
+ *    0: If there isn't a sufficiently large hole at the hint addr.
+ *    addr: If sufficient VA space is available at the hint address;
+ *          or MAP_FIXED was specified.
+ */
+unsigned long generic_mmap_hint(struct file *filp, unsigned long addr,
+				unsigned long len, unsigned long pgoff,
+				unsigned long flags)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma, *prev;
+	const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
+
+	/* requested length too big for entire address space */
+	if (len > mmap_end - mmap_min_addr)
+		return -ENOMEM;
+
+	if (flags & MAP_FIXED)
+		return addr;
+
+	if (!addr)
+		return 0;
+
+	addr = PAGE_ALIGN(addr);
+	vma = find_vma_prev(mm, addr, &prev);
+	if (mmap_end - len >= addr && addr >= mmap_min_addr &&
+	    (!vma || addr + len <= vm_start_gap(vma)) &&
+	    (!prev || addr >= vm_end_gap(prev)))
+		return addr;
+
+	/* Fallback to VA space search */
+	return 0;
+}
+
 /* Get an address range which is currently unmapped.
  * For shmat() with addr=0.
  *
@@ -637,25 +678,13 @@ generic_get_unmapped_area(struct file *f
 			  unsigned long flags, vm_flags_t vm_flags)
 {
 	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma, *prev;
 	struct vm_unmapped_area_info info = {};
 	const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
 
-	if (len > mmap_end - mmap_min_addr)
-		return -ENOMEM;
-
-	if (flags & MAP_FIXED)
+	addr = generic_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
 		return addr;
 
-	if (addr) {
-		addr = PAGE_ALIGN(addr);
-		vma = find_vma_prev(mm, addr, &prev);
-		if (mmap_end - len >= addr && addr >= mmap_min_addr &&
-		    (!vma || addr + len <= vm_start_gap(vma)) &&
-		    (!prev || addr >= vm_end_gap(prev)))
-			return addr;
-	}
-
 	info.length = len;
 	info.low_limit = mm->mmap_base;
 	info.high_limit = mmap_end;
@@ -685,27 +714,14 @@ generic_get_unmapped_area_topdown(struct
 				  unsigned long len, unsigned long pgoff,
 				  unsigned long flags, vm_flags_t vm_flags)
 {
-	struct vm_area_struct *vma, *prev;
 	struct mm_struct *mm = current->mm;
 	struct vm_unmapped_area_info info = {};
 	const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
 
-	/* requested length too big for entire address space */
-	if (len > mmap_end - mmap_min_addr)
-		return -ENOMEM;
-
-	if (flags & MAP_FIXED)
-		return addr;
-
 	/* requesting a specific address */
-	if (addr) {
-		addr = PAGE_ALIGN(addr);
-		vma = find_vma_prev(mm, addr, &prev);
-		if (mmap_end - len >= addr && addr >= mmap_min_addr &&
-				(!vma || addr + len <= vm_start_gap(vma)) &&
-				(!prev || addr >= vm_end_gap(prev)))
-			return addr;
-	}
+	addr = generic_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
+		return addr;
 
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
_

Patches currently in -mm which might be from kaleshsingh@google.com 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