> On Nov 23, 2022, at 5:08 AM, Anders Blomdell <anders.blomdell@xxxxxxxxxxxxxx> wrote: > > Our problems turned out to be a fallout of Al Viros's splice rework, where nfsd reads with non-zero offsets and not ending > on a page boundary failed to remap the last page. I belive that this is a decent fix for that problem (tested on v6.1-rc6, > 6.0.7 and 6.0.9) > > ---- a/fs/nfsd/vfs.c > +++ b/fs/nfsd/vfs.c > @@ -873,7 +873,7 @@ nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf, > unsigned offset = buf->offset; > page += offset / PAGE_SIZE; > - for (int i = sd->len; i > 0; i -= PAGE_SIZE) > + for (int i = sd->len + offset % PAGE_SIZE; i > 0; i -= PAGE_SIZE) > svc_rqst_replace_page(rqstp, page++); > if (rqstp->rq_res.page_len == 0) // first call > rqstp->rq_res.page_base = offset % PAGE_SIZE; Hello Anders, I will wait for Al's review. The official version of your patch will need to include Signed-off-by and Fixes tags. > On 2022-11-11 20:35, Anders Blomdell wrote: >> The text below is an excerpt of https://bugzilla.redhat.com/show_bug.cgi?id=2142132 >> Description of problem: >> Virtual machines that boots from nfs mounted qcow2 images fails to boot when >> the nfs server runs kernel 6.0.5 >> The erros are often >> Booting from Hard Disk... >> GRUB loading. >> Welcome to GRUB! >> error ../../grub-core/kern/dl.c:ELF header smaller than expected. >> Entering rescue mode... >> grub rescue> >> Version-Release number of selected component (if applicable): >> qemu-6.2.0-16.fc36.x86_64 >> kernel-6.0.5-200.fc36.x86_64 >> How reproducible: >> always >> Steps to Reproduce: >> 1. Run a virtual machine with boot disk qcow2 formatted mounted from an nfs server >> running kernel-6.0.5-200.fc36.x86_64 >> Actual results: >> Machine fails to boot >> Expected results: >> Clean boot >> Additional info: >> Git repo is linux-stable >> A git bisect lands me at 310d9d5a5009a93377200b98daa2d84aa2bd8160 >> So commit 746de1f86fcd works >> But cherry picking f0f6b614f83d 310d9d5a5009 bfbfb6182ad1 on top of 746de1f86fcd is broken. >> The bfbfb6182ad1 is picked due to the commit comment >> commit bfbfb6182ad1d7d184b16f25165faad879147f79 >> Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx> >> Date: Sat Sep 10 22:14:02 2022 +0100 >> nfsd_splice_actor(): handle compound pages >> pipe_buffer might refer to a compound page (and contain more than a PAGE_SIZE >> worth of data). Theoretically it had been possible since way back, but >> nfsd_splice_actor() hadn't run into that until copy_page_to_iter() change. >> Fortunately, the only thing that changes for compound pages is that we >> need to stuff each relevant subpage in and convert the offset into offset >> in the first subpage. >> Acked-by: Chuck Lever <chuck.lever@xxxxxxxxxx> >> Tested-by: Benjamin Coddington <bcodding@xxxxxxxxxx> >> Fixes: f0f6b614f83d "copy_page_to_iter(): don't split high-order page in case of ITER_PIPE" >> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> >> The bisect I did: >> git bisect start >> # status: waiting for both good and bad commits >> # bad: [3829606fc5dffeccdf80aebeed3aa75255257f35] Linux 6.0.5 >> git bisect bad 3829606fc5dffeccdf80aebeed3aa75255257f35 >> # status: waiting for good commit(s), bad commit known >> # good: [0b0649b1d27a768d37f23acf4d88e6e90cca7856] Linux 5.19.4 >> git bisect good 0b0649b1d27a768d37f23acf4d88e6e90cca7856 >> # good: [0b0649b1d27a768d37f23acf4d88e6e90cca7856] Linux 5.19.4 >> git bisect good 0b0649b1d27a768d37f23acf4d88e6e90cca7856 >> # good: [3d7cb6b04c3f3115719235cc6866b10326de34cd] Linux 5.19 >> git bisect good 3d7cb6b04c3f3115719235cc6866b10326de34cd >> # good: [7c5c3a6177fa9646884114fc7f2e970b0bc50dc9] Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm >> git bisect good 7c5c3a6177fa9646884114fc7f2e970b0bc50dc9 >> # bad: [eeac7730418563152b0e3172bce9bac4ff6d6bc4] perf pmu-events: Avoid passing pmu_events_map >> git bisect bad eeac7730418563152b0e3172bce9bac4ff6d6bc4 >> # good: [f20c95b46b8fa3ad34b3ea2e134337f88591468b] Merge tag 'tpmdd-next-v5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd >> git bisect good f20c95b46b8fa3ad34b3ea2e134337f88591468b >> # good: [c993e07be023acdeec8e84e2e0743c52adb5fc94] Merge tag 'dma-mapping-5.20-2022-08-06' of git://git.infradead.org/users/hch/dma-mapping >> git bisect good c993e07be023acdeec8e84e2e0743c52adb5fc94 >> # good: [e2ebff9c57fe4eb104ce4768f6ebcccf76bef849] vfs: Check the truncate maximum size in inode_newsize_ok() >> git bisect good e2ebff9c57fe4eb104ce4768f6ebcccf76bef849 >> # good: [c8a684e2e110376c58f0bfa30fb3855d1e319670] Merge tag 'leds-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds >> git bisect good c8a684e2e110376c58f0bfa30fb3855d1e319670 >> # good: [c72687614b3627b3ea55d8d169e31cac70f56f3e] Merge tag 'rpmsg-v5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux >> git bisect good c72687614b3627b3ea55d8d169e31cac70f56f3e >> # bad: [f30adc0d332fdfe5315cb98bd6a7ff0d5cf2aa38] Merge tag 'pull-work.iov_iter-rebased' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs >> git bisect bad f30adc0d332fdfe5315cb98bd6a7ff0d5cf2aa38 >> # good: [60349fd52ecbb8b14545ff25aba2f2e230c4d618] remoteproc: using pm_runtime_resume_and_get instead of pm_runtime_get_sync >> git bisect good 60349fd52ecbb8b14545ff25aba2f2e230c4d618 >> # good: [8520008417c581c4c22e39597f92b9814ae34c31] fold __pipe_get_pages() into pipe_get_pages() >> git bisect good 8520008417c581c4c22e39597f92b9814ae34c31 >> # good: [746de1f86fcd33464acac047f111eea877f2f7a0] pipe_get_pages(): switch to append_pipe() >> git bisect good 746de1f86fcd33464acac047f111eea877f2f7a0 >> # good: [5d5d353bed32dc3ea52e2619e0d1c60b17133b91] Merge tag 'rproc-v5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux >> git bisect good 5d5d353bed32dc3ea52e2619e0d1c60b17133b91 >> # bad: [f0f6b614f83dbae99d283b7b12ab5dd2e04df979] copy_page_to_iter(): don't split high-order page in case of ITER_PIPE >> git bisect bad f0f6b614f83dbae99d283b7b12ab5dd2e04df979 >> # bad: [310d9d5a5009a93377200b98daa2d84aa2bd8160] expand those iov_iter_advance()... >> git bisect bad 310d9d5a5009a93377200b98daa2d84aa2bd8160 >> # first bad commit: [310d9d5a5009a93377200b98daa2d84aa2bd8160] expand those iov_iter_advance()... > > -- > Anders Blomdell Email: anders.blomdell@xxxxxxxxxxxxxx > Department of Automatic Control > Lund University Phone: +46 46 222 4625 > P.O. Box 118 > SE-221 00 Lund, Sweden -- Chuck Lever
