On Mon, 16 Sept 2024 at 15:41, 'Bart Van Assche' via syzkaller <syzkaller@xxxxxxxxxxxxxxxx> wrote: > > On 9/16/24 6:28 AM, Dmitry Vyukov wrote: > > On Fri, 3 Feb 2023 at 19:11, Bart Van Assche <bvanassche@xxxxxxx> wrote: > >> > >> On 2/3/23 00:53, syzbot wrote: > >>> syzbot has bisected this issue to: > >>> > >>> commit 82ede9c19839079e7953a47895729852a440080c > >>> Author: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx> > >>> Date: Tue Jun 21 14:46:53 2022 +0000 > >>> > >>> scsi: ufs: core: Fix typos in error messages > >> > >> To the syzbot maintainers: I think this is a good example of a bisection > >> result that is wrong. It is unlikely that fixing typos in kernel > >> messages would affect whether or not the kernel hangs. Additionally, as > >> far as I know, the systems used by syzbot (Google Compute Engine virtual > >> machines) do trigger any code in the UFS driver. > > > > Hi Bart, > > > > syzbot has logic to detect commits that don't affect builds. > > It hashes SHF_ALLOC vmlinux sections to check if the commit actually > > has any effect on the binary: > > https://github.com/google/syzkaller/blob/c673ca06b23cea94091ab496ef62c3513e434585/pkg/build/linux.go#L253-L286 > > > > Bug CONFIG_UFS_FS is enabled on syzbot, it has some coverage for it, > > and strings affect the binary (can actually be the root cause for > > bugs). So I don't see what else can be done here automatically. > > CONFIG_UFS_FS controls whether or not the UFS filesystem is enabled > (fs/ufs/). The UFS driver is unrelated to the UFS filesystem and is > controlled by CONFIG_SCSI_UFSHCD. Support for the UFS driver has been > added recently in Qemu. Does that mean that it should be possible to > test the UFS driver with syzbot? See also > https://patchew.org/QEMU/20230616065816epcms2p82787f1aeb410ec4b8ab6ffedb6edf4d2@epcms2p8/ Oh, I see. Added this example to the issue: https://github.com/google/syzkaller/issues/2297#issuecomment-2352986387 I've tried to follow all guidelines from reproducible builds: https://docs.kernel.org/kbuild/reproducible-builds.html https://github.com/google/syzkaller/blob/c673ca06b23cea94091ab496ef62c3513e434585/pkg/build/linux.go#L165-L176 https://github.com/google/syzkaller/blob/c673ca06b23cea94091ab496ef62c3513e434585/pkg/build/linux.go#L85-L102 Yet this commit still somehow affected the build: culprit signature: c1512384fd0e6d2bd48b3a1ce2034eb5c0de195562eca27cd2c0c6ac58cd4863 parent signature: 1f86ef314029ed6e1f240aae874259f4bb0f7978f8b38b29d6c184b82965b331 I've debugged and fixed some of these non-determinism bugs, but it seems something is still broken (not sure if it's the compiler, or kbuild, or how we do deterministic build).
