Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: [TEST] page tables filling non-highmem | Date | Mon, 18 Feb 2002 02:59:26 +0100 |
| |
On February 18, 2002 02:38 am, Andrea Arcangeli wrote: > On Fri, Feb 15, 2002 at 09:59:45AM +0100, Daniel Phillips wrote: > > On February 15, 2002 05:51 am, William Lee Irwin III wrote: > > > The following testcase brought down 2.4.17 mainline on an > > > 8-way P-III 700MHz machine with 12GB of RAM. The last thing > > > logged from it was a LowFree of 2MB with 9GB of highmem free > > > after something like 6-8 hours of pounding away, at which > > > time the machine stopped responding (IIRC it was given ~12 > > > hours to echo another character). > > > > > > This testcase is a blatant attempt to fill the direct-mapped > > > portion of the kernel virtual address space with process pagetables. > > > It was suspected such a thing was happening in another failure scenario > > > which is what motivated me to devise this testcase. I believe a fix > > > already exists (i.e. aa's ptes in highmem stuff) though I've not yet > > > verified its correct operation here. > > > > As you described it to me on irc, this demonstration turns up a > > considerably worse problem than just having insufficient space for > > page tables - the system locks up hard instead of doing anything > > reasonable on page table-related oom. It's wrong that the system > > should behave this way, it is after all, just an oom. > > > > Now that basic stability issues seem to be under control, perhaps > > it's time to give the oom problem the attention it deserves? > > My tree doesn't lock up hard even without pte-highmem applied. The task > gets killed.
Well, the obvious question is: Why Isn't It In Mainline???
> backout pte-highmem, try the same testcase again on my tree > and you'll see. The oom handling in mainline is deadlock prone, I always > known this and that's why I always rejected it. Nobody but me > acklowledged this problem
Lots of people acknowleged it, it seems just one guy fixed it.
> and I spent quite an amount of time convincing > mainline maintainers about those deadlock flaws of the mainline approch > but I failed so I giveup waiting for a report like this, just like with > all the other stuff that is now in my vm patch, 90% of it I tried to > push it separately into mainline before having to accumulate it.
What I'd suggest is, just post a list of each item outstanding item that haven't been pushed to mainline, and an explanation of which problem it fixes.
Incorrect oom accounting has been a bleeding wound for well over a year, and if you've got a fix that's provably correct...
Marcelo?? Is this just a stupid communication problem?
-- Daniel - 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/
| |