On 11/24, KOSAKI Motohiro wrote: > > Hi > > > 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? > > Because, If the pages of argv is swapping out when processing execve, > This accouing doesn't work. Why? If copy_strings() inserts the new page into bprm->vma and then this page is swapped out, inc_mm_counter(current->mm, MM_ANONPAGES) becomes incorrect, yes. And we can't turn it into MM_SWAPENTS. But does this really matter? oom_badness() counts MM_ANONPAGES + MM_SWAPENTS, and result is the same. > Is this enough explanation? Please don't hesitate say "no". If people > don't like my approach, I don't hesitate change my thinking. Well, certainly I can't say no ;) But it would be nice to find a more simple fix (if it can work, of course). And. I need a simple solution for the older kernels. Oleg. -- 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>