linux-kernel - Re: [PATCH v2] module: Don't wait for GOING modules

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Message-ID: <Y8g9lTBnCgB7g08/@bombadil.infradead.org>
Date:   Wed, 18 Jan 2023 10:42:29 -0800
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Petr Pavlu <petr.pavlu@...e.com>
Cc:     Petr Mladek <pmladek@...e.com>,
        Prarit Bhargava <prarit@...hat.com>,
        Vegard Nossum <vegard.nossum@...cle.com>,
        Borislav Petkov <bp@...en8.de>, NeilBrown <neilb@...e.de>,
        Goldwyn Rodrigues <rgoldwyn@...e.com>, david@...hat.com,
        mwilck@...e.com, linux-modules@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v2] module: Don't wait for GOING modules

On Wed, Jan 18, 2023 at 04:12:05PM +0100, Petr Pavlu wrote:
> On 1/18/23 01:04, Luis Chamberlain wrote:
> > The rationale for making a regression fix with a new userspace return value
> > is fair given the old fix made things even much worse the point some kernel
> > boots would fail. So the rationale to suggest we *must* short-cut
> > parallel loads as effectively as possible seems sensible *iff* that
> > could not make things worse too but sadly I've found an isssue
> > proactively with this fix, or at least that this issue is also not fixed:
> > 
> > ./tools/testing/selftests/kmod/kmod.sh -t 0006
> > Tue Jan 17 23:18:13 UTC 2023
> > Running test: kmod_test_0006 - run #0
> > kmod_test_0006: OK! - loading kmod test
> > kmod_test_0006: FAIL, test expects SUCCESS (0) - got -EINVAL (-22)
> > ----------------------------------------------------
> > Custom trigger configuration for: test_kmod0
> > Number of threads:      50
> > Test_case:      TEST_KMOD_FS_TYPE (2)
> > driver: test_module
> > fs:     xfs
> > ----------------------------------------------------
> > Test completed
> > 
> > When can multiple get_fs_type() calls be issued on a system? When
> > mounting a large number of filesystems. Sadly though this issue seems
> > to have gone unnoticed for a while now. Even reverting commit
> > 6e6de3dee51a doesn't fix it, and I've run into issues with trying
> > to bisect, first due to missing Kees' patch which fixes a compiler
> > failure on older kernel [0] and now I'm seeing this while trying to
> > build v5.1:
> > 
> > ld: arch/x86/boot/compressed/pgtable_64.o:(.bss+0x0): multiple definition of `__force_order';
> > arch/x86/boot/compressed/kaslr_64.o:(.bss+0x0): first defined here
> > ld: warning: arch/x86/boot/compressed/efi_thunk_64.o: missing .note.GNU-stack section implies executable stack
> > ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
> > ld: arch/x86/boot/compressed/head_64.o: warning: relocation in read-only section `.head.text'
> > ld: warning: arch/x86/boot/compressed/vmlinux has a LOAD segment with RWX permissions
> > ld: warning: creating DT_TEXTREL in a PIE
> > make[2]: *** [arch/x86/boot/compressed/Makefile:118: arch/x86/boot/compressed/vmlinux] Error 1
> > make[1]: *** [arch/x86/boot/Makefile:112: arch/x86/boot/compressed/vmlinux] Error 2
> > make: *** [arch/x86/Makefile:283: bzImage] Error 2
> > 
> > [0] http://lore.kernel.org/lkml/20220213182443.4037039-1-keescook@chromium.org
> > 
> > But we should try to bisect to see what cauased the above kmod test 0006
> > to start failing.
> 
> It is not clear to me from your description if the observed failure of
> kmod_test_0006 is related to the fix in this thread.

The issue happens with and without the patch in this thread, I'd just hate to
exacerbate the issue further.

> The problem was not possible for me to reproduce on my system. My test was on
> an 8-CPU x86_64 machine using v6.2-rc4 with "defconfig + kvm_guest.config +
> tools/testing/selftests/kmod/config".

With the patch?

> Could you perhaps trace the test to determine where the EINVAL value comes
> from?

Sure, it'll take a bit.

  Luis