+ mm-utilc-added-page-count-to-__vm_enough_memory-failure-warning.patch added to mm-unstable branch

+ mm-utilc-added-page-count-to-__vm_enough_memory-failure-warning.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/util.c: add page count to __vm_enough_memory failure warning
has been added to the -mm mm-unstable branch.  Its filename is
     mm-utilc-added-page-count-to-__vm_enough_memory-failure-warning.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-utilc-added-page-count-to-__vm_enough_memory-failure-warning.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: Matthew Cassell <mcassell411@gmail.com>
Subject: mm/util.c: add page count to __vm_enough_memory failure warning
Date: Wed, 21 Feb 2024 16:02:35 +0000

Commit 44b414c8715c5dcf53288 ("mm/util.c: add warning if
__vm_enough_memory fails") adds debug information which gives the process
id and executable name should __vm_enough_memory() fail.  Adding the
number of pages to the failure message would benefit application
developers and system administrators in debugging overambitious memory
requests by providing a point of reference to the amount of memory causing
__vm_enough_memory() to fail.

1. Set appropriate kernel tunable to reach code path for failure
   message:

	# echo 2 > /proc/sys/vm/overcommit_memory

2. Test program to generate failure - requests 1 gibibyte per iteration:

	#include <stdlib.h>
	#include <stdio.h>

	int main(int argc, char **argv) {
		for(;;) {
			if(malloc(1<<30) == NULL)
				break;

			printf("allocated 1 GiB\n");
		}

		return 0;
	}

3. Output:

	Before:

	__vm_enough_memory: pid: 1218, comm: a.out, not enough
memory for the allocation

	After:

	__vm_enough_memory: pid: 1141, comm: a.out, pages: 262145, not
enough memory for the allocation

Link: https://lkml.kernel.org/r/20240221160235.1771-1-mcassell411@gmail.com
Signed-off-by: Matthew Cassell <mcassell411@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Yongqiang Liu <liuyongqiang13@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/util.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/mm/util.c~mm-utilc-added-page-count-to-__vm_enough_memory-failure-warning
+++ a/mm/util.c
@@ -976,8 +976,8 @@ int __vm_enough_memory(struct mm_struct
 	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
 		return 0;
 error:
-	pr_warn_ratelimited("%s: pid: %d, comm: %s, not enough memory for the allocation\n",
-			    __func__, current->pid, current->comm);
+	pr_warn_ratelimited("%s: pid: %d, comm: %s, pages: %ld, not enough memory for the allocation\n",
+			    __func__, current->pid, current->comm, pages);
 	vm_unacct_memory(pages);
 
 	return -ENOMEM;
_

Patches currently in -mm which might be from mcassell411@gmail.com are

mm-utilc-added-page-count-to-__vm_enough_memory-failure-warning.patch