+ tools-mm-prevent-page_owner_sort-from-truncating-input.patch added to mm-nonmm-unstable branch

The patch titled
     Subject: tools/mm: prevent page_owner_sort from truncating input
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     tools-mm-prevent-page_owner_sort-from-truncating-input.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/tools-mm-prevent-page_owner_sort-from-truncating-input.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Warren Xiong <[email protected]>
Subject: tools/mm: prevent page_owner_sort from truncating input
Date: Thu, 30 Jul 2026 09:58:09 +0800

page_owner_sort opens the output file with "w" before reading the input. 
If both paths refer to the same file, this truncates the input and the
tool silently processes zero records before returning success.

Delay opening the output file until all input records have been loaded
into memory.  This allows the tool to sort a file in place without
truncating data before it has been consumed.

Link: https://lore.kernel.org/[email protected]
Signed-off-by: Warren Xiong <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Cc: Vishal Moola <[email protected]>
Cc: Ye Liu <[email protected]>
Cc: Zhen Ni <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 tools/mm/page_owner_sort.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/tools/mm/page_owner_sort.c~tools-mm-prevent-page_owner_sort-from-truncating-input
+++ a/tools/mm/page_owner_sort.c
@@ -836,8 +836,7 @@ int main(int argc, char **argv)
 	}
 
 	fin = fopen(argv[optind], "r");
-	fout = fopen(argv[optind + 1], "w");
-	if (!fin || !fout) {
+	if (!fin) {
 		usage();
 		perror("open: ");
 		exit(1);
@@ -874,6 +873,13 @@ int main(int argc, char **argv)
 			goto out_free;
 	}
 
+	fout = fopen(argv[optind + 1], "w");
+	if (!fout) {
+		usage();
+		perror("open: ");
+		exit(1);
+	}
+
 	printf("loaded %d\n", list_size);
 
 	printf("sorting ....\n");
_

Patches currently in -mm which might be from [email protected] are

tools-mm-prevent-page_owner_sort-from-truncating-input.patch