Messages in this thread | | | Date | Fri, 20 Mar 2009 00:00:17 -0700 | Subject | Re: ftruncate-mmap: pages are lost after writing to mmaped file. | From | Ying Han <> |
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On Thu, Mar 19, 2009 at 5:49 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote: > > > On Thu, 19 Mar 2009, Ying Han wrote: >> > >> > Ying Han - since you're all set up for testing this and have reproduced it >> > on multiple kernels, can you try it on a few more kernel versions? It >> > would be interesting to both go further back in time (say 2.6.15-ish), >> > _and_ check something like 2.6.21 which had the exact dirty accounting >> > fix. Maybe it's not really an old bug - maybe we re-introduced a bug that >> > was fixed for a while. >> >> I tried 2.6.24 for couple of hours and the problem not happening yet. While >> the same test on 2.6.25, the problem happen right away. > > Ok, so 2.6.25 is known bad. Can you test 2.6.24 a lot more, because we > should not decide that it's bug-free without a _lot_ of testing. > > But if it's a bug that has gone away and then re-appeared, it at least > explains how 2.6.21 (which got a fair amount of mmap testing) didn't have > lots of reports of mmap corruption. > > That said, I can think of nothing obvious in between 2.6.24 and .25 that > would have re-introduced it. But if some heavy testing really does confirm > that 2.6.24 doesn't have the problem, that is a good first step to trying > to narrow down where things started going wrong. > > That said, it could _easily_ be some timing-related pattern. One of the > things in between 2.6.24 and .25 is > > - 8bc3be2751b4f74ab90a446da1912fd8204d53f7: "writeback: speed up > writeback of big dirty files" > > which is that exact kind of "change the timing patterns, but don't change > anything fundamental" thing. > > Which is why I'd like you to continue testing 2.6.24 just to be _really_ > sure that it really doesn't happen there.
Unfortunately, 2.6.24 is not immune. After running several hours, i triggered the problem. > > Linus > -- 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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