Dear Dave, >> ... What is unacceptable is that PAE crashes or freezes with OOM: >> it should gracefully handle the issue. Noting that (for a machine >> with 4GB or under) PAE fails where the HIGHMEM4G kernel succeeds ... > > You have found a delta, but you're not really making apples-to-apples > comparisons. The page tables ... I understand that the exact sizes of page tables are very important to developers. To the rest of us, all that matters is that the kernel moves them to highmem or swap or whatever, that it maybe emits some error message but that it does not crash or freeze. > There's probably a bug here. But, it's incredibly unlikely to be seen > in practice on anything resembling a modern system. ... Probably, I found the bug on a very modern and brand-new system, just trying to copy a few ISO image files and trying to log in a hundred students. My machine crashed under those very practical and normal circumstances. The demos with dd and sleep were just that: easily reproducible demos. > ... easily worked around by upgrading to a 64-bit kernel ... Do you mean that PAE should never be used, but to use amd64 instead? > ... Raising the vm.min_free_kbytes sysctl (to perhaps 10x of > its current value on your system) is likely to help the hangs too, > although it will further "consume" lowmem. I have tried that, it did not work. As you say, it is backward. > ... for a bug with ... so many reasonable workarounds ... Only one workaround was proposed: use amd64. PAE is buggy and useless, should be deprecated and removed. Cheers, Paul Paul Szabo psz@xxxxxxxxxxxxxxxxx http://www.maths.usyd.edu.au/u/psz/ School of Mathematics and Statistics University of Sydney Australia -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>