On Fri, Apr 26, 2019 at 11:05:17AM +1000, David Gibson wrote: > On Thu, Apr 25, 2019 at 08:19:58AM +0200, Christoph Hellwig wrote: > > Just curious: What exact trees do you see this with? This area > > changed a lot with the multipage bvec support, and subsequent fixes. > > So, I tried it with 576ed913 itself and with 576ed913^ to verify that > it didn't happen there. The problem also occurred with Linus' tree as > of when I started bisecting, which appears to have been 444fe991. > Actually, come to that, here's the whole bisect log in case it's > helpful: > > # git bisect log > git bisect start > # good: [bebc6082da0a9f5d47a1ea2edc099bf671058bd4] Linux 4.14 > git bisect good bebc6082da0a9f5d47a1ea2edc099bf671058bd4 > # bad: [444fe991353987c1c9bc5ab1f903d01f1b4ad415] Merge tag > 'riscv-for-linus-5.1-rc6' of > git://git.kernel.org/pub/scm/linux/kernel/git/palmer/riscv-linux > git bisect bad 444fe991353987c1c9bc5ab1f903d01f1b4ad415 > # good: [399c4129eba6145924ab90363352b7bdcd554751] Merge tag > 'pxa-for-4.19-dma_slave_map' of https://github.com/rjarzmik/linux > git bisect good 399c4129eba6145924ab90363352b7bdcd554751 > # bad: [73b6f96cbc0162787bcbdac5f538167084c8d605] Merge branch > 'drm-fixes-4.20' of git://people.freedesktop.org/~agd5f/linux into drm-fixes > git bisect bad 73b6f96cbc0162787bcbdac5f538167084c8d605 > # good: [85a585918fb4122ad26b6febaec5c3c90bf2535c] Merge tag > 'loadpin-security-next' of > https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux into next-loadpin > git bisect good 85a585918fb4122ad26b6febaec5c3c90bf2535c > # bad: [3acbd2de6bc3af215c6ed7732dfc097d1e238503] Merge tag 'sound-4.20-rc1' > of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound > git bisect bad 3acbd2de6bc3af215c6ed7732dfc097d1e238503 > # good: [8f18da47211554f1ef674fef627c05f23b75a8e0] Merge branch 'master' of > git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next > git bisect good 8f18da47211554f1ef674fef627c05f23b75a8e0 > # bad: [0d1b82cd8ac2e8856ae9045c97782ac1c359929c] Merge branch > 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip > git bisect bad 0d1b82cd8ac2e8856ae9045c97782ac1c359929c > # bad: [1650ac53066577a5e83fe3e9d992c9311597ff8c] Merge tag 'mmc-v4.20' of > git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc > git bisect bad 1650ac53066577a5e83fe3e9d992c9311597ff8c > # bad: [6ab9e09238fdfd742fe23b81e2d385a1cab49d9b] Merge tag > 'for-4.20/block-20181021' of git://git.kernel.dk/linux-block > git bisect bad 6ab9e09238fdfd742fe23b81e2d385a1cab49d9b > # good: [528985117126f11beea339cf39120ee99da04cd2] Merge tag 'arm64-upstream' > of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux > git bisect good 528985117126f11beea339cf39120ee99da04cd2 > # bad: [2cf99bbd106f89fc72f778e8ad9d5538f1ef939b] lightnvm: pblk: add helpers > for chunk addresses > git bisect bad 2cf99bbd106f89fc72f778e8ad9d5538f1ef939b > # bad: [33b14f67a4e1eabd219fd6543da8f15ed86b641c] nvme: register ns_id > attributes as default sysfs groups > git bisect bad 33b14f67a4e1eabd219fd6543da8f15ed86b641c > # bad: [27ca1d4ed04ea29dc77b47190a3cc82697023e76] block: move > req_gap_back_merge to blk.h > git bisect bad 27ca1d4ed04ea29dc77b47190a3cc82697023e76 > # bad: [07b05bcc3213ac9f8c28c9d835b4bf3d5798cc60] blkcg: convert > blkg_lookup_create to find closest blkg > git bisect bad 07b05bcc3213ac9f8c28c9d835b4bf3d5798cc60 > # good: [cbeb869a3d1110450186b738199963c5e68c2a71] block, bfq: correctly > charge and reset entity service in all cases > git bisect good cbeb869a3d1110450186b738199963c5e68c2a71 > # bad: [576ed9135489c723fb39b97c4e2c73428d06dd78] block: use bio_add_page in > bio_iov_iter_get_pages > git bisect bad 576ed9135489c723fb39b97c4e2c73428d06dd78 > # good: [c8765de0adfcaaf4ffb2d951e07444f00ffa9453] blok, bfq: do not plug I/O > if all queues are weight-raised > git bisect good c8765de0adfcaaf4ffb2d951e07444f00ffa9453 > # first bad commit: [576ed9135489c723fb39b97c4e2c73428d06dd78] block: use > bio_add_page in bio_iov_iter_get_pages > > The problem also occurred with the RHEL8 downstream kernel tree. > That's based on 4.18, but has 576ed913 backported. > > > So I'd be really curious if it can be reproduced with Jens' latest > > block for-5.2 tree (which should be in latest linux-next). > > I'll see if I can try that when I next get access to the machine.
Ok, I've now had a chance to test the next-20190423 tree.
I can still reproduce the problem: in fact it is substantially worse,
and somewhat more consistent.
Previously I usually lost 2-3 hugepages per run, though I'd
occasionally seen other values between 0 and 8. With the next tree, I
lost 46 hugepages on most runs, though I also saw 45 and 48
occasionally.
Hope this is illuminating.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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