On 10/25, KOSAKI Motohiro wrote:
>
> Because execve() makes new mm struct and setup stack and
> copy argv. It mean the task have two mm while execve() temporary.
> Unfortunately this nascent mm is not pointed any tasks, then
> OOM-killer can't detect this memory usage. therefore OOM-killer
> may kill incorrect task.
>
> Thus, this patch added signal->in_exec_mm member and track
> nascent mm usage.
Stupid question.
Can't we just account these allocations in the old -mm temporary?
IOW. Please look at the "patch" below. It is of course incomplete
and wrong (to the point inc_mm_counter() is not safe without
SPLIT_RSS_COUNTING), and copy_strings/flush_old_exec are not the
best places to play with mm-counters, just to explain what I mean.
It is very simple. copy_strings() increments MM_ANONPAGES every
time we add a new page into bprm->vma. This makes this memory
visible to select_bad_process().
When exec changes ->mm (or if it fails), we change MM_ANONPAGES
counter back.
Most probably I missed something, but what do you think?
Oleg.
--- x/include/linux/binfmts.h
+++ x/include/linux/binfmts.h
@@ -29,6 +29,7 @@ struct linux_binprm{
char buf[BINPRM_BUF_SIZE];
#ifdef CONFIG_MMU
struct vm_area_struct *vma;
+ unsigned long mm_anonpages;
#else
# define MAX_ARG_PAGES 32
struct page *page[MAX_ARG_PAGES];
--- x/fs/exec.c
+++ x/fs/exec.c
@@ -457,6 +457,9 @@ static int copy_strings(int argc, const
goto out;
}
+ bmrp->mm_anonpages--;
+ inc_mm_counter(current->mm, MM_ANONPAGES);
+
if (kmapped_page) {
flush_kernel_dcache_page(kmapped_page);
kunmap(kmapped_page);
@@ -1003,6 +1006,7 @@ int flush_old_exec(struct linux_binprm *
/*
* Release all of the old mmap stuff
*/
+ add_mm_counter(current->mm, bprm->mm_anonpages);
retval = exec_mmap(bprm->mm);
if (retval)
goto out;
@@ -1426,8 +1430,10 @@ int do_execve(const char * filename,
return retval;
out:
- if (bprm->mm)
- mmput (bprm->mm);
+ if (bprm->mm) {
+ add_mm_counter(current->mm, bprm->mm_anonpages);
+ mmput(bprm->mm);
+ }
out_file:
if (bprm->file) {
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>