[merged mm-stable] mm-add-merging-after-mremap-resize.patch removed from -mm tree

[merged mm-stable] mm-add-merging-after-mremap-resize.patch removed from -mm tree

[Andrew Morton]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 5754 bytes --]


The quilt patch titled
     Subject: mm: add merging after mremap resize
has been removed from the -mm tree.  Its filename was
     mm-add-merging-after-mremap-resize.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Jakub Matěna <matenajakub@gmail.com>
Subject: mm: add merging after mremap resize
Date: Fri, 3 Jun 2022 16:57:19 +0200

When mremap call results in expansion, it might be possible to merge the
VMA with the next VMA which might become adjacent.  This patch adds
vma_merge call after the expansion is done to try and merge.

[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/20220603145719.1012094-3-matenajakub@gmail.com
Signed-off-by: Jakub Matěna <matenajakub@gmail.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mremap.c                              |   19 +++++++-
 tools/testing/selftests/vm/mremap_test.c |   49 ++++++++++++++++++++-
 2 files changed, 65 insertions(+), 3 deletions(-)

--- a/mm/mremap.c~mm-add-merging-after-mremap-resize
+++ a/mm/mremap.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/mm.h>
+#include <linux/mm_inline.h>
 #include <linux/hugetlb.h>
 #include <linux/shm.h>
 #include <linux/ksm.h>
@@ -23,6 +24,7 @@
 #include <linux/mmu_notifier.h>
 #include <linux/uaccess.h>
 #include <linux/userfaultfd_k.h>
+#include <linux/mempolicy.h>
 
 #include <asm/cacheflush.h>
 #include <asm/tlb.h>
@@ -1012,6 +1014,9 @@ SYSCALL_DEFINE5(mremap, unsigned long, a
 		/* can we just expand the current mapping? */
 		if (vma_expandable(vma, new_len - old_len)) {
 			long pages = (new_len - old_len) >> PAGE_SHIFT;
+			unsigned long extension_start = addr + old_len;
+			unsigned long extension_end = addr + new_len;
+			pgoff_t extension_pgoff = vma->vm_pgoff + (old_len >> PAGE_SHIFT);
 
 			if (vma->vm_flags & VM_ACCOUNT) {
 				if (security_vm_enough_memory_mm(mm, pages)) {
@@ -1020,8 +1025,18 @@ SYSCALL_DEFINE5(mremap, unsigned long, a
 				}
 			}
 
-			if (vma_adjust(vma, vma->vm_start, addr + new_len,
-				       vma->vm_pgoff, NULL)) {
+			/*
+			 * Function vma_merge() is called on the extension we are adding to
+			 * the already existing vma, vma_merge() will merge this extension with
+			 * the already existing vma (expand operation itself) and possibly also
+			 * with the next vma if it becomes adjacent to the expanded vma and
+			 * otherwise compatible.
+			 */
+			vma = vma_merge(mm, vma, extension_start, extension_end,
+					vma->vm_flags, vma->anon_vma, vma->vm_file,
+					extension_pgoff, vma_policy(vma),
+					vma->vm_userfaultfd_ctx, anon_vma_name(vma));
+			if (!vma) {
 				vm_unacct_memory(pages);
 				ret = -ENOMEM;
 				goto out;
--- a/tools/testing/selftests/vm/mremap_test.c~mm-add-merging-after-mremap-resize
+++ a/tools/testing/selftests/vm/mremap_test.c
@@ -119,6 +119,50 @@ static unsigned long long get_mmap_min_a
 }
 
 /*
+ * This test validates that merge is called when expanding a mapping.
+ * Mapping containing three pages is created, middle page is unmapped
+ * and then the mapping containing the first page is expanded so that
+ * it fills the created hole. The two parts should merge creating
+ * single mapping with three pages.
+ */
+static void mremap_expand_merge(unsigned long page_size)
+{
+	char *test_name = "mremap expand merge";
+	FILE *fp;
+	char *line = NULL;
+	size_t len = 0;
+	bool success = false;
+	char *start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	munmap(start + page_size, page_size);
+	mremap(start, page_size, 2 * page_size, 0);
+
+	fp = fopen("/proc/self/maps", "r");
+	if (fp == NULL) {
+		ksft_test_result_fail("%s\n", test_name);
+		return;
+	}
+
+	while (getline(&line, &len, fp) != -1) {
+		char *first = strtok(line, "- ");
+		void *first_val = (void *)strtol(first, NULL, 16);
+		char *second = strtok(NULL, "- ");
+		void *second_val = (void *) strtol(second, NULL, 16);
+
+		if (first_val == start && second_val == start + 3 * page_size) {
+			success = true;
+			break;
+		}
+	}
+	if (success)
+		ksft_test_result_pass("%s\n", test_name);
+	else
+		ksft_test_result_fail("%s\n", test_name);
+	fclose(fp);
+}
+
+/*
  * Returns the start address of the mapping on success, else returns
  * NULL on failure.
  */
@@ -336,6 +380,7 @@ int main(int argc, char **argv)
 	int i, run_perf_tests;
 	unsigned int threshold_mb = VALIDATION_DEFAULT_THRESHOLD;
 	unsigned int pattern_seed;
+	int num_expand_tests = 1;
 	struct test test_cases[MAX_TEST];
 	struct test perf_test_cases[MAX_PERF_TEST];
 	int page_size;
@@ -407,12 +452,14 @@ int main(int argc, char **argv)
 				(threshold_mb * _1MB >= _1GB);
 
 	ksft_set_plan(ARRAY_SIZE(test_cases) + (run_perf_tests ?
-		      ARRAY_SIZE(perf_test_cases) : 0));
+		      ARRAY_SIZE(perf_test_cases) : 0) + num_expand_tests);
 
 	for (i = 0; i < ARRAY_SIZE(test_cases); i++)
 		run_mremap_test_case(test_cases[i], &failures, threshold_mb,
 				     pattern_seed);
 
+	mremap_expand_merge(page_size);
+
 	if (run_perf_tests) {
 		ksft_print_msg("\n%s\n",
 		 "mremap HAVE_MOVE_PMD/PUD optimization time comparison for 1GB region:");
_

Patches currently in -mm which might be from matenajakub@gmail.com are