Hello,

New build issue found on stable-rc/linux-5.4.y:

--- GCC does not allow variable declarations in for loop initializers before C99 [-Wgcc-compat] in mm/mempool.o (mm/mempool.c) [logspec:kbuild,kbuild.compiler.warning] ---

- dashboard: https://d.kernelci.org/i/maestro:d414057925e4dea9704ce677eef188319c8610a4 - giturl: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git - commit HEAD: b11ac6e8f913ac67f9424a5cdd4158b283c0e3cb

Please include the KernelCI tag when submitting a fix:

Reported-by: kernelci.org bot bot@kernelci.org

Log excerpt: ===================================================== mm/mempool.c:69:8: warning: GCC does not allow variable declarations in for loop initializers before C99 [-Wgcc-compat] 69 | for (int i = 0; i < (1 << order); i++) { | ^ CC arch/arm/mach-imx/mach-vpr200.o mm/mempool.c:71:17: error: implicit declaration of function 'kmap_local_page' [-Werror,-Wimplicit-function-declaration] 71 | void *addr = kmap_local_page(page + i); | ^ mm/mempool.c:71:17: note: did you mean 'kmap_to_page'? ./include/linux/highmem.h:67:14: note: 'kmap_to_page' declared here 67 | struct page *kmap_to_page(void *addr); | ^ mm/mempool.c:71:10: error: incompatible integer to pointer conversion initializing 'void *' with an expression of type 'int' [-Wint-conversion] 71 | void *addr = kmap_local_page(page + i); | ^ ~~~~~~~~~~~~~~~~~~~~~~~~~ mm/mempool.c:74:4: error: implicit declaration of function 'kunmap_local' [-Werror,-Wimplicit-function-declaration] 74 | kunmap_local(addr); | ^ mm/mempool.c:103:8: warning: GCC does not allow variable declarations in for loop initializers before C99 [-Wgcc-compat] 103 | for (int i = 0; i < (1 << order); i++) { | ^ mm/mempool.c:105:17: error: implicit declaration of function 'kmap_local_page' [-Werror,-Wimplicit-function-declaration] 105 | void *addr = kmap_local_page(page + i); | ^ mm/mempool.c:105:10: error: incompatible integer to pointer conversion initializing 'void *' with an expression of type 'int' [-Wint-conversion] 105 | void *addr = kmap_local_page(page + i); | ^ ~~~~~~~~~~~~~~~~~~~~~~~~~ mm/mempool.c:108:4: error: implicit declaration of function 'kunmap_local' [-Werror,-Wimplicit-function-declaration] 108 | kunmap_local(addr); | ^ 2 warnings and 6 errors generated.

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# Builds where the incident occurred:

## defconfig+allmodconfig+CONFIG_FRAME_WARN=2048 on (arm): - compiler: clang-21 - config: https://files.kernelci.org/kbuild-clang-21-arm-allmodconfig-69286c4df5b8743b... - dashboard: https://d.kernelci.org/build/maestro:69286c4df5b8743b1f65f308

#kernelci issue maestro:d414057925e4dea9704ce677eef188319c8610a4

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