Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 29 Apr 2003 21:52:59 -0700 | From | William Lee Irwin III <> | Subject | Re: must-fix list for 2.6.0 |
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William Lee Irwin III <wli@holomorphy.com> wrote: >> I didn't notice anything specific here about sys_remap_file_pages() vs. >> truncate() (sans objrmap); did a fix fly by that I didn't notice, >> or was it less of an issue than I thought it was?
On Tue, Apr 29, 2003 at 09:45:37PM -0700, Andrew Morton wrote: > That's just a bug. We can either go through and unmap all the pages via > their rmap chains, or mark the vma as nonlinear and just anonymise the pages > and to heck with the SIGBUS. I'm not particularly fussed either way > really...
Okay, I'll just fill in if no one else appears to do the busywork.
William Lee Irwin III <wli@holomorphy.com> wrote: >> Also, the OOM killer fails to check lowmem; basically it just needs >> - if (nr_swap_pages > 0) >> + if (nr_swap_pages > 0 && nr_free_buffer_pages() > 0) >> With that in addition to the OOM killer locking patch I posted and >> another to completely eliminate mm-less processes from consideration >> 64GB ia32 (with, of course, my oversized out-of-tree patch) recovers >> from OOM instead of deadlocking after a mass-killing with swap online.
On Tue, Apr 29, 2003 at 09:45:37PM -0700, Andrew Morton wrote: > Wanna send patch?
Absolutely; I'll arrange a more organized presentation around Thursday (yes, I'm among the last-minute OLS people -- it couldn't be helped).
William Lee Irwin III <wli@holomorphy.com> wrote: >> I'd be interested in more detailed descriptions of the user-level no >> overcommit, dcacheicache, and truncated ext3 page issues after Thursday.
On Tue, Apr 29, 2003 at 09:45:37PM -0700, Andrew Morton wrote: > The arithmetic in vm_enough_memory() is woefully inaccurate. If you have no > swap and then build up a lot of icache/dcache, vm_enough_memory() > underestimates the amount of reclaimable memory by a lot and big mallocs > fail. If the i/dcache has internal fragmentation it gets even worse. > I had a brief poke at that a while ago and decided it was basically hopeless. > I suspect that assuming "all slab pages are reclaimable" would be the best > fix here.
It sounds like some thought may be necessary if the above approach is to be improved upon.
On Tue, Apr 29, 2003 at 09:45:37PM -0700, Andrew Morton wrote: > The ext3 truncate pages are those pages which are on the LRU and have > buffers, but that's _all_ they have. They are instantly reclaimable and are > basically free memory. Only nobody knows that yet, so vm_enough_memory() > gets it wrong. The fix would be to nail these pages more aggressively in > journal_unmap_buffer(), or to account for them and include that accounting in > vm_emough_memory(). I'd prefer to just free the dang pages in > journal_unmap_buffer().
Noted.
William Lee Irwin III <wli@holomorphy.com> wrote: >> The latter sounds easy to address. It actually sounds like a 2.4.x >> compatibility fix.
On Tue, Apr 29, 2003 at 09:45:37PM -0700, Andrew Morton wrote: > davem thinks we shouldn't need it, and I've seen no bug reports that indicate > that we _do_ need it, but Andi says we do. > Certainly something needs to be done in that area - a ppc64 box with 16G of > memory (all ZONE_DMA) cruises along with just 1M of memory free.
Okay, I'll classify that as a back-burner issue.
Thanks.
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