threads / bug / 56804

bug: invalid sha1 pointer in cache-tree

Subject: bug: invalid sha1 pointer in cache-tree

## tl;dr

2 messages between Oct 29, 2021 and Nov 2, 2021.

replies: 1people: 2as markdown or json

Joel Stanley· Oct 29, 2021, 05:57 UTC · lore

Hello,

I've filled out git-bugreport after discussing this issue with a git developer. I'm not sure if it's user error, disk corruption, or a bug in git. Any insight would be appreciated!

What did you do before the bug happened? (Steps to reproduce your issue)

I was attempting to merge a tag into the current branch. Before I did so, I reset'd away a commit I didn't want:

$ git reset HEAD~1 --hard error: Could not read 7c03aa457205afa2def273129653bea6225c5a0a HEAD is now at 387b8b425339 spi: fsi: Print status on error

I fetched the tag I was after:

$ git fetch  stable
From https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux
   ed99bf0e81b5..2760370b1649  linux-4.14.y         -> stable/linux-4.14.y
   e34184f53363..ff079d726eb6  linux-4.19.y         -> stable/linux-4.19.y
   1392fe82d7fb..c67099a5bc53  linux-4.4.y          -> stable/linux-4.4.y
   9e8a7b701479..aa13f01432a2  linux-4.9.y          -> stable/linux-4.9.y
   5aa003b38148..3a9842b42e42  linux-5.10.y         -> stable/linux-5.10.y
   924356b31dcb..fe024e004fa3  linux-5.14.y         -> stable/linux-5.14.y
   faaca480fd5c..4f508aa9dd3b  linux-5.4.y          -> stable/linux-5.4.y
   080735f6de74..dddcb86bb323  linux-rolling-lts    -> stable/linux-rolling-lts
   66035107bbad..cc0dfcda549b  linux-rolling-stable ->
stable/linux-rolling-stable
   5d6ab0bb408f..3906fe9bb7f1  master               -> stable/master
 * [new tag]                   v4.14.251            -> v4.14.251
 * [new tag]                   v4.14.252            -> v4.14.252
 * [new tag]                   v4.19.211            -> v4.19.211
 * [new tag]                   v4.19.212            -> v4.19.212
 * [new tag]                   v4.19.213            -> v4.19.213
 * [new tag]                   v4.4.289             -> v4.4.289
 * [new tag]                   v4.9.287             -> v4.9.287
 * [new tag]                   v5.10.73             -> v5.10.73
 * [new tag]                   v5.10.74             -> v5.10.74
 * [new tag]                   v5.10.75             -> v5.10.75
 * [new tag]                   v5.14.12             -> v5.14.12
 * [new tag]                   v5.14.13             -> v5.14.13
 * [new tag]                   v5.14.14             -> v5.14.14
 * [new tag]                   v5.15-rc5            -> v5.15-rc5
 * [new tag]                   v5.15-rc6            -> v5.15-rc6
 * [new tag]                   v5.15-rc7            -> v5.15-rc7
 * [new tag]                   v5.4.153             -> v5.4.153
 * [new tag]                   v5.4.154             -> v5.4.154
 * [new tag]                   v5.4.155             -> v5.4.155

This is the merge. I hadn't touched any of these files (I don't work on arch/xtensa at all), so this was unexpected:

$ git merge v5.14.14
error: Your local changes to the following files would be overwritten by merge:
  arch/xtensa/include/uapi/asm/Kbuild
arch/xtensa/include/uapi/asm/auxvec.h
arch/xtensa/include/uapi/asm/byteorder.h
arch/xtensa/include/uapi/asm/ioctls.h
arch/xtensa/include/uapi/asm/ipcbuf.h
arch/xtensa/include/uapi/asm/mman.h
arch/xtensa/include/uapi/asm/msgbuf.h
arch/xtensa/include/uapi/asm/param.h
arch/xtensa/include/uapi/asm/poll.h
arch/xtensa/include/uapi/asm/posix_types.h
arch/xtensa/include/uapi/asm/ptrace.h
arch/xtensa/include/uapi/asm/sembuf.h
arch/xtensa/include/uapi/asm/setup.h
arch/xtensa/include/uapi/asm/shmbuf.h
arch/xtensa/include/uapi/asm/sigcontext.h
arch/xtensa/include/uapi/asm/signal.h
arch/xtensa/include/uapi/asm/sockios.h
arch/xtensa/include/uapi/asm/stat.h
arch/xtensa/include/uapi/asm/swab.h
arch/xtensa/include/uapi/asm/termbits.h
arch/xtensa/include/uapi/asm/types.h
arch/xtensa/include/uapi/asm/unistd.h arch/xtensa/kernel/.gitignore
arch/xtensa/kernel/Makefile arch/xtensa/kernel/align.S
arch/xtensa/kernel/asm-offsets.c arch/xtensa/kernel/coprocessor.S
arch/xtensa/kernel/entry.S arch/xtensa/kernel/head.S
arch/xtensa/kernel/hw_breakpoint.c arch/xtensa/kernel/irq.c
arch/xtensa/kernel/jump_label.c arch/xtensa/kernel/mcount.S
arch/xtensa/kernel/module.c arch/xtensa/kernel/mxhead.S
arch/xtensa/kernel/pci-dma.c arch/xtensa/kernel/pci.c
arch/xtensa/kernel/perf_event.c arch/xtensa/kernel/platform.c
arch/xtensa/kernel/process.c arch/xtensa/kernel/ptrace.c
arch/xtensa/kernel/s32c1i_selftest.c arch/xtensa/kernel/setup.c
arch/xtensa/kernel/signal.c arch/xtensa/kernel/smp.c
arch/xtensa/kernel/stacktrace.c arch/xtensa/kernel/syscall.c
arch/xtensa/kernel/syscalls/Makefile
arch/xtensa/kernel/syscalls/syscall.tbl arch/xtensa/kernel/time.c
arch/xtensa/kernel/traps.c arch/xtensa/kernel/vectors.S
arch/xtensa/kernel/vmlinux.lds.S arch/xtensa/kernel/xtensa_ksyms.c
arch/xtensa/lib/Makefile arch/xtensa/lib/checksum.S
arch/xtensa/lib/memcopy.S arch/xtensa/lib/memset.S
arch/xtensa/lib/pci-auto.c arch/xtensa/lib/strncpy_user.S
arch/xtensa/lib/strnlen_user.S arch/xtensa/lib/usercopy.S
arch/xtensa/mm/Makefile arch/xtensa/mm/cache.c arch/xtensa/mm/fault.c
arch/xtensa/mm/highmem.c arch/xtensa/mm/init.c
arch/xtensa/mm/ioremap.c arch/xtensa/mm/kasan_init.c
arch/xtensa/mm/misc.S arch/xtensa/mm/mmu.c arch/xtensa/mm/tlb.c
arch/xtensa/platforms/iss/Makefile arch/xtensa/platforms/iss/console.c
arch/xtensa/platforms/iss/include/platform/serial.h
arch/xtensa/platforms/iss/include/platform/simcall-gdbio.h
arch/xtensa/platforms/iss/include/platform/simcall-iss.h
arch/xtensa/platforms/iss/include/platform/simcall.h
arch/xtensa/platforms/iss/network.c arch/xtensa/platforms/iss/setup.c
arch/xtensa/platforms/iss/simdisk.c
arch/xtensa/platforms/xt2000/Makefile
arch/xtensa/platforms/xt2000/include/platform/hardware.h
arch/xtensa/platforms/xt2000/include/platform/serial.h
arch/xtensa/platforms/xt2000/setup.c
arch/xtensa/platforms/xtfpga/Makefile
arch/xtensa/platforms/xtfpga/include/platform/hardware.h
arch/xtensa/platforms/xtfpga/include/platform/lcd.h
arch/xtensa/platforms/xtfpga/include/platform/serial.h
arch/xtensa/platforms/xtfpga/lcd.c
arch/xtensa/platforms/xtfpga/setup.c
arch/xtensa/variants/csp/include/variant/core.h
arch/xtensa/variants/csp/include/variant/tie-asm.h
arch/xtensa/variants/csp/include/variant/tie.h
arch/xtensa/variants/dc232b/include/variant/core.h
arch/xtensa/variants/dc232b/include/variant/tie-asm.h
arch/xtensa/variants/dc232b/include/variant/tie.h
arch/xtensa/variants/dc233c/include/variant/core.h
arch/xtensa/variants/dc233c/include/variant/tie-asm.h
arch/xtensa/variants/dc233c/include/variant/tie.h
arch/xtensa/variants/de212/include/variant/core.h
arch/xtensa/variants/de212/include/variant/tie-asm.h
arch/xtensa/variants/de212/include/variant/tie.h
arch/xtensa/variants/fsf/include/variant/core.h
arch/xtensa/variants/fsf/include/variant/tie-asm.h
arch/xtensa/variants/fsf/include/variant/tie.h
arch/xtensa/variants/test_kc705_be/include/variant/core.h
arch/xtensa/variants/test_kc705_be/include/variant/tie-asm.h
arch/xtensa/variants/test_kc705_b
$ git status
On branch dev-5.14
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
    new file:   arch/xtensa/include/uapi/asm/Kbuild
    new file:   arch/xtensa/include/uapi/asm/auxvec.h
    new file:   arch/xtensa/include/uapi/asm/byteorder.h
    new file:   arch/xtensa/include/uapi/asm/ioctls.h
    new file:   arch/xtensa/include/uapi/asm/ipcbuf.h
    new file:   arch/xtensa/include/uapi/asm/mman.h
    new file:   arch/xtensa/include/uapi/asm/msgbuf.h
    new file:   arch/xtensa/include/uapi/asm/param.h
    new file:   arch/xtensa/include/uapi/asm/poll.h
    new file:   arch/xtensa/include/uapi/asm/posix_types.h
    new file:   arch/xtensa/include/uapi/asm/ptrace.h
    new file:   arch/xtensa/include/uapi/asm/sembuf.h
    new file:   arch/xtensa/include/uapi/asm/setup.h
    new file:   arch/xtensa/include/uapi/asm/shmbuf.h
    new file:   arch/xtensa/include/uapi/asm/sigcontext.h
    new file:   arch/xtensa/include/uapi/asm/signal.h
    new file:   arch/xtensa/include/uapi/asm/sockios.h
    new file:   arch/xtensa/include/uapi/asm/stat.h
    new file:   arch/xtensa/include/uapi/asm/swab.h
    new file:   arch/xtensa/include/uapi/asm/termbits.h
    new file:   arch/xtensa/include/uapi/asm/types.h
    new file:   arch/xtensa/include/uapi/asm/unistd.h
    new file:   arch/xtensa/kernel/.gitignore
    new file:   arch/xtensa/kernel/Makefile
    new file:   arch/xtensa/kernel/align.S
    new file:   arch/xtensa/kernel/asm-offsets.c
    new file:   arch/xtensa/kernel/coprocessor.S
    new file:   arch/xtensa/kernel/entry.S
    new file:   arch/xtensa/kernel/head.S
    new file:   arch/xtensa/kernel/hw_breakpoint.c
    new file:   arch/xtensa/kernel/irq.c
    new file:   arch/xtensa/kernel/jump_label.c
    new file:   arch/xtensa/kernel/mcount.S
    new file:   arch/xtensa/kernel/module.c
    new file:   arch/xtensa/kernel/mxhead.S
    new file:   arch/xtensa/kernel/pci-dma.c
    new file:   arch/xtensa/kernel/pci.c
    new file:   arch/xtensa/kernel/perf_event.c
    new file:   arch/xtensa/kernel/platform.c
    new file:   arch/xtensa/kernel/process.c
    new file:   arch/xtensa/kernel/ptrace.c
    new file:   arch/xtensa/kernel/s32c1i_selftest.c
    new file:   arch/xtensa/kernel/setup.c
    new file:   arch/xtensa/kernel/signal.c
    new file:   arch/xtensa/kernel/smp.c
    new file:   arch/xtensa/kernel/stacktrace.c
    new file:   arch/xtensa/kernel/syscall.c
    new file:   arch/xtensa/kernel/syscalls/Makefile
    new file:   arch/xtensa/kernel/syscalls/syscall.tbl
    new file:   arch/xtensa/kernel/time.c
    new file:   arch/xtensa/kernel/traps.c
    new file:   arch/xtensa/kernel/vectors.S
    new file:   arch/xtensa/kernel/vmlinux.lds.S
    new file:   arch/xtensa/kernel/xtensa_ksyms.c
    new file:   arch/xtensa/lib/Makefile
    new file:   arch/xtensa/lib/checksum.S
    new file:   arch/xtensa/lib/memcopy.S
    new file:   arch/xtensa/lib/memset.S
    new file:   arch/xtensa/lib/pci-auto.c
    new file:   arch/xtensa/lib/strncpy_user.S
    new file:   arch/xtensa/lib/strnlen_user.S
    new file:   arch/xtensa/lib/usercopy.S
    new file:   arch/xtensa/mm/Makefile
    new file:   arch/xtensa/mm/cache.c
    new file:   arch/xtensa/mm/fault.c
    new file:   arch/xtensa/mm/highmem.c
    new file:   arch/xtensa/mm/init.c
    new file:   arch/xtensa/mm/ioremap.c
    new file:   arch/xtensa/mm/kasan_init.c
    new file:   arch/xtensa/mm/misc.S
    new file:   arch/xtensa/mm/mmu.c
    new file:   arch/xtensa/mm/tlb.c
    new file:   arch/xtensa/platforms/iss/Makefile
    new file:   arch/xtensa/platforms/iss/console.c
    new file:   arch/xtensa/platforms/iss/include/platform/serial.h
    new file:   arch/xtensa/platforms/iss/include/platform/simcall-gdbio.h
    new file:   arch/xtensa/platforms/iss/include/platform/simcall-iss.h
    new file:   arch/xtensa/platforms/iss/include/platform/simcall.h
    new file:   arch/xtensa/platforms/iss/network.c
    new file:   arch/xtensa/platforms/iss/setup.c
    new file:   arch/xtensa/platforms/iss/simdisk.c
    new file:   arch/xtensa/platforms/xt2000/Makefile
    new file:   arch/xtensa/platforms/xt2000/include/platform/hardware.h
    new file:   arch/xtensa/platforms/xt2000/include/platform/serial.h
    new file:   arch/xtensa/platforms/xt2000/setup.c
    new file:   arch/xtensa/platforms/xtfpga/Makefile
    new file:   arch/xtensa/platforms/xtfpga/include/platform/hardware.h
    new file:   arch/xtensa/platforms/xtfpga/include/platform/lcd.h
    new file:   arch/xtensa/platforms/xtfpga/include/platform/serial.h
    new file:   arch/xtensa/platforms/xtfpga/lcd.c
    new file:   arch/xtensa/platforms/xtfpga/setup.c
    new file:   arch/xtensa/variants/csp/include/variant/core.h
    new file:   arch/xtensa/variants/csp/include/variant/tie-asm.h
    new file:   arch/xtensa/variants/csp/include/variant/tie.h
    new file:   arch/xtensa/variants/dc232b/include/variant/core.h
    new file:   arch/xtensa/variants/dc232b/include/variant/tie-asm.h
    new file:   arch/xtensa/variants/dc232b/include/variant/tie.h
    new file:   arch/xtensa/variants/dc233c/include/variant/core.h
    new file:   arch/xtensa/variants/dc233c/include/variant/tie-asm.h
    new file:   arch/xtensa/variants/dc233c/include/variant/tie.h
    new file:   arch/xtensa/variants/de212/include/variant/core.h
    new file:   arch/xtensa/variants/de212/include/variant/tie-asm.h
    new file:   arch/xtensa/variants/de212/include/variant/tie.h
    new file:   arch/xtensa/variants/fsf/include/variant/core.h
    new file:   arch/xtensa/variants/fsf/include/variant/tie-asm.h
    new file:   arch/xtensa/variants/fsf/include/variant/tie.h
    new file:   arch/xtensa/variants/test_kc705_be/include/variant/core.h
    new file:   arch/xtensa/variants/test_kc705_be/include/variant/tie-asm.h
    new file:   arch/xtensa/variants/test_kc705_be/include/variant/tie.h
    new file:   arch/xtensa/variants/test_kc705_hifi/include/variant/core.h
    new file:   arch/xtensa/variants/test_kc705_hifi/include/variant/tie-asm.h
    new file:   arch/xtensa/variants/test_kc705_hifi/include/variant/tie.h
    new file:   arch/xtensa/variants/test_mmuhifi_c3/include/variant/core.h
    new file:   arch/xtensa/variants/test_mmuhifi_c3/include/variant/tie-asm.h
    new file:   arch/xtensa/variants/test_mmuhifi_c3/include/variant/tie.h

I cleaned up the working tree (rm -rf arch/xtensa && git reset --hard) and re-attempted the merge:

$ git merge v5.14.14 fatal: unable to read tree 7c03aa457205afa2def273129653bea6225c5a0a

This is the error I now see when I re-attempt the merge.

What did you expect to happen? (Expected behavior)

The tag to be merged.

What happened instead? (Actual behavior)

The merge failed:

$ git merge v5.14.14 fatal: unable to read tree 7c03aa457205afa2def273129653bea6225c5a0a

What's different between what you expected and what actually happened?

I expected the merge to complete successfully.

Anything else you want to add:

I have tree git trees involved:

linus, a clone of torvald's tree stable, a bare clone of the stable tree. it was cloned with a --reference to linus openbmc, a clone of a kernel tree that has a --reference to both stable and linus.

I did a fsck and saw this:

error: 7c03aa457205afa2def273129653bea6225c5a0a: invalid sha1 pointer
in cache-tree
broken link from    tree 385b33c97554b2ab43b7dea822b34e10e9d7ce66 (:)
              to    tree 7c03aa457205afa2def273129653bea6225c5a0a (:configs/)

I have since tried re-fetching all three repositories in turn, and this had no change:

git fetch-pack --all https://github.com/openbmc/linux git fetch-pack --all git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch-pack --all git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

I also tried removing and re-cloning the stable tree (an the assumption that this is where the objects that make up the problematic v5.14.14 tag should come from), but this did not help. I have however changed the output of git fsck:

$ git merge v5.14.14 fatal: unable to read tree 385b33c97554b2ab43b7dea822b34e10e9d7ce66

$ git fsck
...
error: 385b33c97554b2ab43b7dea822b34e10e9d7ce66: invalid sha1 pointer
in cache-tree
broken link from    tree 61a337aed7681b506b935b507a422fc5983ba4f3 (:)
              to    tree 385b33c97554b2ab43b7dea822b34e10e9d7ce66 (:powerpc/)

Please review the rest of the bug report below. You can delete any lines you don't wish to share.

[System Info] git version: git version 2.33.0 cpu: x86_64 no commit associated with this build sizeof-long: 8 sizeof-size_t: 8 shell-path: /bin/sh uname: Linux 5.14.0-2-amd64 #1 SMP Debian 5.14.9-2 (2021-10-03) x86_64 compiler info: gnuc: 10.2 libc info: glibc: 2.33 $SHELL (typically, interactive shell): /bin/bash

[Enabled Hooks]

Cheers,

Joel

Emily Shaffer· Nov 2, 2021, 17:06 UTC · re: Joel Stanley · lore

Re: bug: invalid sha1 pointer in cache-tree

Hi Joel, hopefully someone can correct me for being wrong about this ;)

On Thu, Oct 28, 2021 at 10:57 PM Joel Stanley <joel@jms.id.au> wrote:

Show 15 quoted lines

>
> Hello,
>
> I've filled out git-bugreport after discussing this issue with a git
> developer. I'm not sure if it's user error, disk corruption, or a bug
> in git. Any insight would be appreciated!
>
> What did you do before the bug happened? (Steps to reproduce your issue)
>
> I was attempting to merge a tag into the current branch. Before I did so, I
> reset'd away a commit I didn't want:
>
> $ git reset HEAD~1 --hard
> error: Could not read 7c03aa457205afa2def273129653bea6225c5a0a
> HEAD is now at 387b8b425339 spi: fsi: Print status on error

I suspect you already had problems from this point, regardless of what came after. What's surprising to me, though, is that the object 7c03aa would be missing, since it should have been referred to by the current branch you were trying to merge into.

Is it possible you were doing something slightly odd, like partial clone, shallow clone, or working in detached-HEAD for some reason? You didn't mention here that you had been rm-ing things in .git/, and I asked you explicitly about that when we spoke offline, but that also would worry me.

Regardless, I think once you've got a missing object and 'git fsck' fails, there aren't many promises we can make about correct behavior after, so I'm not sure I have anything to say on the rest of the report, unfortunately.

Show 9 quoted lines

> Anything else you want to add:
>
> I have tree git trees involved:
>
> linus, a clone of torvald's tree
> stable, a bare clone of the stable tree. it was cloned with a
> --reference to linus
> openbmc, a clone of a kernel tree that has a --reference to both
> stable and linus.

Ah, this is a hint and may actually be the winner... When you're cloning with --reference, the "referenced" repo doesn't know who is referencing it, so it sometimes can gc with abandon and delete something you cared about in a referencing repo.

The workarounds here range from "if you care only about network speed, reclone with --reference --dissociate" to "if you care about network speed *and* disk space, do something fancy with 'git worktree' and multiple remotes" to "if you care about disk space *and* you care about insulating objects from accidentally going to the wrong remote, get a bigger disk and use --reference --dissociate anyway".

Show 24 quoted lines

>
> I did a fsck and saw this:
>
> error: 7c03aa457205afa2def273129653bea6225c5a0a: invalid sha1 pointer
> in cache-tree
> broken link from    tree 385b33c97554b2ab43b7dea822b34e10e9d7ce66 (:)
>               to    tree 7c03aa457205afa2def273129653bea6225c5a0a (:configs/)
>
>
> I have since tried re-fetching all three repositories in turn, and
> this had no change:
>
> git fetch-pack --all https://github.com/openbmc/linux
> git fetch-pack --all
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> git fetch-pack --all
> git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
>
> I also tried removing and re-cloning the stable tree (an the assumption that
> this is where the objects that make up the problematic v5.14.14 tag should come
> from), but this did not help. I have however changed the output of git fsck:
>
> $ git merge v5.14.14
> fatal: unable to read tree 385b33c97554b2ab43b7dea822b34e10e9d7ce66

Yeah, I think this is the final decisive pointer to "this is an issue with stable as an alternate to your other stuff" - I'd guess that the object that's missing changed because the alternate links broke in some way.

Show 32 quoted lines

>
> $ git fsck
> ...
> error: 385b33c97554b2ab43b7dea822b34e10e9d7ce66: invalid sha1 pointer
> in cache-tree
> broken link from    tree 61a337aed7681b506b935b507a422fc5983ba4f3 (:)
>               to    tree 385b33c97554b2ab43b7dea822b34e10e9d7ce66 (:powerpc/)
>
>
> Please review the rest of the bug report below.
> You can delete any lines you don't wish to share.
>
>
> [System Info]
> git version:
> git version 2.33.0
> cpu: x86_64
> no commit associated with this build
> sizeof-long: 8
> sizeof-size_t: 8
> shell-path: /bin/sh
> uname: Linux 5.14.0-2-amd64 #1 SMP Debian 5.14.9-2 (2021-10-03) x86_64
> compiler info: gnuc: 10.2
> libc info: glibc: 2.33
> $SHELL (typically, interactive shell): /bin/bash
>
>
> [Enabled Hooks]
>
> Cheers,
>
> Joel