Messages in this thread | | | Date | Sat, 6 Nov 2004 08:05:16 -0200 | From | Marcelo Tosatti <> | Subject | Re: [PATCH] Remove OOM killer from try_to_free_pages / all_unreclaimable braindamage |
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On Sat, Nov 06, 2004 at 02:20:18AM +0100, Andrea Arcangeli wrote: > On Fri, Nov 05, 2004 at 03:32:50PM -0800, Jesse Barnes wrote: > > On Friday, November 05, 2004 12:01 pm, Marcelo Tosatti wrote: > > > In my opinion the correct approach is to trigger the OOM killer > > > when kswapd is unable to free pages. Once that is done, the number > > > of tasks inside page reclaim is irrelevant. > > > > That makes sense.
Hi Andrea,
> I don't like it, kswapd may fail balancing because there's a GFP_DMA > allocation that eat the last dma page, but we should not kill tasks if > we fail to balance in kswapd, we should kill tasks only when no fail > path exists (i.e. only during page faults, everything else in the kernel > has a fail path and it should never trigger oom).
The OOM killer is only going to get triggered if kswapd is not able to make _any_ progress in all zones. So it wont "fail balancing because there's a GFP_DMA allocation that eat the last dma page".
As long as frees _one_ page during all passes from DEF_PRIORITY till priority=0, it wont kill any task. See?
I dont get your point.
> If you move it in kswapd there's no way to prevent oom-killing from a > syscall allocation (I guess even right now it would go wrong in this > sense, but at least right now it's more fixable).
I dont understand what you mean. "prevent oom-killing from a syscall allocation" ?
> I want to move the oom > kill outside the alloc_page paths. The oom killing is all about the page > faults not having a fail path, and in turn the oom killing should be > moved in the page fault code, not in the allocator. Everything else > should keep returning -ENOMEM to the caller.
Isnt OOM killing all about the reclaiming efforts not being able to make progress?
> So to me moving the oom killer into kswapd looks a regression.
To me having tasks trigger the OOM kill is fundamentally broken because it doesnt take into account kswapd page freeing efforts which are in-progress at the very moment.
That makes senses a lot of sense to me - would love to be proved wrong.
See, its completly screwed right now. The code inside out_of_memory() which only triggers OOM if it has happened several times during the past few seconds is horrible and shows how bad it is. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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