Messages in this thread Patch in this message | | | From | Matthew Cassell <> | Subject | [PATCH] mm/util.c: Added page count to __vm_enough_memory failure warning | Date | Wed, 21 Feb 2024 16:02:35 +0000 |
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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
Signed-off-by: Matthew Cassell <mcassell411@gmail.com> --- mm/util.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/util.c b/mm/util.c index 5a6a9802583b..c0afb56f16ea 100644 --- a/mm/util.c +++ b/mm/util.c @@ -976,8 +976,8 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 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; -- 2.43.2
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