linux-kernel - [linux-next-20250422] Build failure: Wvla-larger-than=0 is meaningless

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Message-ID: <7780883c-0ac8-4aaa-b850-469e33b50672@linux.ibm.com>
Date: Wed, 23 Apr 2025 19:11:43 +0530
From: Venkat Rao Bagalkote <venkat88@...ux.ibm.com>
To: Stephen Rothwell <sfr@...b.auug.org.au>, Kees Cook <kees@...nel.org>,
        nathan@...nel.org, hch@....de,
        Madhavan Srinivasan <maddy@...ux.ibm.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        venkat88@...ux.ibm.com
Subject: [linux-next-20250422] Build failure: Wvla-larger-than=0 is
 meaningless

Hello,


I am observing linux-next build failure on IBM Power8 server.


Repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git

Branch: master

GCC: 8.5.0 20210514

ldd (GNU libc) 2.28

Attached is the .config file.


Build errors:


[[01m^[[Kcc1:^[[m^[[K ^[[01;36m^[[Knote: ^[[m^[[K-Wvla-larger-than=0 is 
meaningless
^[[01m^[[Kcc1:^[[m^[[K ^[[01;36m^[[Knote: ^[[m^[[K-Wvla-larger-than=0 is 
meaningless
^[[01m^[[Kcc1:^[[m^[[K ^[[01;36m^[[Knote: ^[[m^[[K-Wvla-larger-than=0 is 
meaningless
^[[01m^[[Kcc1:^[[m^[[K ^[[01;36m^[[Knote: ^[[m^[[K-Wvla-larger-than=0 is 
meaningless
^[[01m^[[Kcc1:^[[m^[[K ^[[01;36m^[[Knote: ^[[m^[[K-Wvla-larger-than=0 is 
meaningless
make[1]: *** [/home/upstreamci/linux/Makefile:2011: .] Error 2
make: *** [Makefile:248: __sub-make] Error 2


Git bisect is pointing to first bad commit as: 
4e5222bc2eef69252277f837880c876bf0ffee04


Git Bisect log:


git bisect start
# status: waiting for both good and bad commits
# good: [9c32cda43eb78f78c73aee4aa344b777714e259b] Linux 6.15-rc3
git bisect good 9c32cda43eb78f78c73aee4aa344b777714e259b
# status: waiting for bad commit, 1 good commit known
# bad: [2c9c612abeb38aab0e87d48496de6fd6daafb00b] Add linux-next 
specific files for 20250422
git bisect bad 2c9c612abeb38aab0e87d48496de6fd6daafb00b
# good: [d1da62193ce9715a3cd25a6007b32284aef3725e] Merge branch 
'drm-next' of https://gitlab.freedesktop.org/drm/kernel.git
git bisect good d1da62193ce9715a3cd25a6007b32284aef3725e
# good: [165991dc7afd1eec364a4b980cf6befdfca84404] next-20250414/tip
git bisect good 165991dc7afd1eec364a4b980cf6befdfca84404
# good: [feaa817f7fbb1bb50f3c6b119098c5940c2e2532] Merge branch 'togreg' 
of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git
git bisect good feaa817f7fbb1bb50f3c6b119098c5940c2e2532
# good: [b7d37856d1bddb8e79a7e27a8605dfbb82fe8e9a] Merge branch 
'for-next' of 
git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux.git
git bisect good b7d37856d1bddb8e79a7e27a8605dfbb82fe8e9a
# good: [77fe94f0d068193c22ce8cfd7ee6317ab2f679c2] Merge branch 'kunit' 
of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git
git bisect good 77fe94f0d068193c22ce8cfd7ee6317ab2f679c2
# good: [627d1af4ec321f81d7ca76f541aef908d5a0e4bd] Merge branch 
'ntb-next' of https://github.com/jonmason/ntb.git
git bisect good 627d1af4ec321f81d7ca76f541aef908d5a0e4bd
# good: [f34fa2aef257678d9534cb3debbceaf453df02cc] Merge branch 
'pin-init-next' of https://github.com/Rust-for-Linux/linux.git
git bisect good f34fa2aef257678d9534cb3debbceaf453df02cc
# good: [9b7c1e4703dbff94ee0a545445f706518fccb73a] Merge branch 
'bitmap-for-next' of https://github.com/norov/linux.git
git bisect good 9b7c1e4703dbff94ee0a545445f706518fccb73a
# bad: [685b6cba6fcbdc4a3b1708ac70aef556f594907c] Merge branch 
'for-next/kspp' of 
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git
git bisect bad 685b6cba6fcbdc4a3b1708ac70aef556f594907c
# good: [431f4fcea79ffe17f396c10cf42d226494d2f489] kunit/usercopy: 
Disable u64 test on 32-bit SPARC
git bisect good 431f4fcea79ffe17f396c10cf42d226494d2f489
# good: [89860db3b0405ccf4419e76eff487544aab4e4d4] overflow: Clarify 
expectations for getting DEFINE_FLEX variable sizes
git bisect good 89860db3b0405ccf4419e76eff487544aab4e4d4
# bad: [c5b45570cac5302cb650531a35142eab8231853c] mod_devicetable: 
Enlarge the maximum platform_device_id name length
git bisect bad c5b45570cac5302cb650531a35142eab8231853c
# bad: [4e5222bc2eef69252277f837880c876bf0ffee04] kbuild: Switch from 
-Wvla to -Wvla-larger-than=0
git bisect bad 4e5222bc2eef69252277f837880c876bf0ffee04
# first bad commit: [4e5222bc2eef69252277f837880c876bf0ffee04] kbuild: 
Switch from -Wvla to -Wvla-larger-than=0


I tried reverting the bad commit, but build fails with something like this.


Build Error after reverting the first bad commit

kernel/watchdog.c: In function 'lockup_detector_reconfigure':
kernel/watchdog.c:936:2: error: too many arguments to function 
'__lockup_detector_reconfigure'
   __lockup_detector_reconfigure(false);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/watchdog.c:926:13: note: declared here
  static void __lockup_detector_reconfigure(void)
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/watchdog.c: In function 'lockup_detector_setup':
kernel/watchdog.c:940:2: error: too many arguments to function 
'__lockup_detector_reconfigure'
   __lockup_detector_reconfigure(false);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/watchdog.c:926:13: note: declared here
  static void __lockup_detector_reconfigure(void)
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/watchdog.c: In function 'proc_watchdog_update':
kernel/watchdog.c:962:2: error: too many arguments to function 
'__lockup_detector_reconfigure'
   __lockup_detector_reconfigure(thresh_changed);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/watchdog.c:926:13: note: declared here
  static void __lockup_detector_reconfigure(void)
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/watchdog.c: At top level:
cc1: warning: unrecognized command line option 
'-Wno-unterminated-string-initialization'
make[3]: *** [scripts/Makefile.build:203: kernel/watchdog.o] Error 1
make[3]: *** Waiting for unfinished jobs....
make[2]: *** [scripts/Makefile.build:461: kernel] Error 2
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [/root/linux-next/Makefile:2011: .] Error 2
make: *** [Makefile:248: __sub-make] Error 2


If you happen to fix this issue, please add below tag.


Reported-by: Venkat Rao Bagalkote <venkat88@...ux.ibm.com>


Regards,

Venkat.

View attachment "Wvla_build_error.config" of type "text/plain" (192816 bytes)