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List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Objtool segfault inside an VM, based on commit 24172e0d7990 From: Qu Wenruo To: LKML , linux-btrfs References: <0b7d3e02-0609-410e-a221-8e68a0bd89b0@gmx.com> Content-Language: en-US Autocrypt: addr=quwenruo.btrfs@gmx.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNIlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT7CwJQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCZxF1YAUJEP5a sQAKCRDCPZHzoSX+qF+mB/9gXu9C3BV0omDZBDWevJHxpWpOwQ8DxZEbk9b9LcrQlWdhFhyn xi+l5lRziV9ZGyYXp7N35a9t7GQJndMCFUWYoEa+1NCuxDs6bslfrCaGEGG/+wd6oIPb85xo 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jXQLdkh44+maXzgcgYd6PBTS+j5EPWrvySBdU0Vm3S4Yqamhwy9MR/lAL5CA== =E5=9C=A8 2025/11/17 13:33, Qu Wenruo =E5=86=99=E9=81=93: >=20 >=20 > =E5=9C=A8 2025/11/17 13:10, Qu Wenruo =E5=86=99=E9=81=93: >> Hi, >> >> Recently I'm hitting pretty frequent objtool crashes, sometimes during= =20 >> module linking (btrfs in my case) sometimes during the vmlinux linking. >> >> Unfortunately I don't have a coredump for it. >> >> The only info so far is from dmesg (and obvious the compile failure): >> >> [=C2=A0 625.066787] traps: objtool[46220] general protection fault=20 >> ip:563ab54c6eb0 sp:7ffd9c2ba7c8 error:0 in=20 >> objtool[19eb0,563ab54b2000+1f000] >> >> The involved VM has the following spec: >> >> - Kernel branch >> =C2=A0=C2=A0 Btrfs' development branch. >> >> =C2=A0=C2=A0 The base commit is 24172e0d79900908cf5ebf366600616d29c9b41= 7, around >> =C2=A0=C2=A0 v6.18-rc6. Furthermore, if just compiling on old kernels (in my case, 6.17.8), I=20 haven't yet hit a linking time segfault. So it's something in the v6.18 release cycle. Not sure if it's the recent Zen5 related hassles. Thanks, Qu >> >> - 10 vCPU, host CPU features pass-through, x86_64 >> =C2=A0=C2=A0 Host is using AMD HX370. >> >> =C2=A0=C2=A0 Haven't yet hit the segfault on aarch64. >> >> - 8G vRAM >> =C2=A0=C2=A0 Thus it should be enough for most cases. >> >> - Toolchain versions: >> =C2=A0=C2=A0 gcc 15.2.1+r301+gf24307422d1d-1 >> =C2=A0=C2=A0 binutils 2.45.1-1 >> >> =C2=A0=C2=A0 All from the latest Archlinux. >> >> =C2=A0=C2=A0 Older gcc (15.2.1+r22+gc4e96a094636-1) and binutils=20 >> (2.45+r29+g2b2e51a31ec7-1) are causing the same segfault. >> >> =C2=A0=C2=A0 Haven't yet tried LLVM. >=20 > Unfortunately LLVM is hitting the same crash. > I'm using llvm/clang/lld 21.1.5. >=20 > So it doesn't look like a toolchain specific bug, but something specific= =20 > to objtool of the kernel. >=20 >=20 > Thanks, > Qu >=20 >> >> - Kernel config >> =C2=A0=C2=A0 Attached. >> >> =C2=A0=C2=A0 Sometimes tweaking the config can workaround the bug a lit= tle, >> =C2=A0=C2=A0 but not reliably. >> >> Is this a known problem and can I work around the segfault? >> >> Thanks, >> Qu >=20 >=20