On Tue, Dec 6, 2011 at 4:55 PM, Hugh Dickins <hughd@xxxxxxxxxx> wrote: > On Mon, 5 Dec 2011, Allison Henderson wrote: >> On 12/05/2011 04:38 PM, Hugh Dickins wrote: >> > >> > This has been outstanding for a month now, and we've heard no progress: >> > please revert commit 02fac1297eb3 "ext4: fix partial page writes" for rc5. >> > >> > The problems appear on a 1k-blocksize filesystem under memory pressure: >> > the hunk in ext4_da_write_end() causes oops, because it's playing with >> > a page after generic_write_end() dropped our last reference to it; and >> > backing out the hunk in ext4_da_write_begin() is then found to stop >> > rare data corruption seen when kbuilding. >> > >> > Although I earlier reported that backing out the patch caused an fsx >> > test to fail earlier, I've since found great variation in how soon it >> > fails, and seen it fail just as quickly with 02fac1297eb3 still in. >> > I also reported that I had to go back to 2.6.38 for fsx not to fail >> > under memory pressure: you won't be surprised that that turned out to >> > be because 2.6.38 defaults nomblk_io_submit but 2.6.39 mblk_io_submit. >> >> Have you tried Yongqiang's patch "[PATCH 1/2] ext4: let mpage_submit_io >> works well when blocksize < pagesize" ? I have tried it and it does seem to >> help, but I am still running into some failures that I am trying to debug, >> but let please let us know if it helps the issues that you are seeing. Thx! > > That 1/2, or the 2/2 "ext4: let ext4_discard_partial_buffers handle > pages without buffers correctly"? The latter is mostly a reversion > of your 02fac1297eb3, so that's the one I need to fix the oops and > rare data corruption. Perhaps you're suggesting 1/2 for fsx failures > under memory pressure? > > I've now tried the fsx test on three machines, with both 1/2 and 2/2 > applied to 3.2-rc4. On one machine, with ext2 on loop on tmpfs, the > fsx test failed in a couple of minutes with those patches; on another > machine, with ext2 on loop on tmpfs, it failed after about 40 minutes > with the patches; on this laptop, with ext2 on SSD, it's just now > failed after 35 minutes with the patches. ext2? So files are indirect mapped? If so, the failure should has nothing to do with punching hole, I remember that punch hole is not supported for indirect mapped files. Do you mean fsx failure or the bug you reported earlier due to referencing a unlocked page? Yongqiang. > > That's not to say that Yongqiang's patches aren't good; but I cannot > detect whether they make any improvement or not, since lasting for 2 or > 40 minutes is typical for fsx under memory pressure with recent kernels. > > Hugh -- Best Wishes Yongqiang Yang -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
