Hello,

New build issue found on stable-rc/linux-5.10.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:edfc0791be4ae7547a2a17054e9cd0317c106f20 - giturl: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git - commit HEAD: 92a27d160c829ca1d8dd3be92e8e8669620d66d5

Please include the KernelCI tag when submitting a fix:

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

Log excerpt: ===================================================== mm/mempool.c:68:8: warning: GCC does not allow variable declarations in for loop initializers before C99 [-Wgcc-compat] 68 | for (int i = 0; i < (1 << order); i++) { | ^ mm/mempool.c:70:17: error: implicit declaration of function 'kmap_local_page' [-Werror,-Wimplicit-function-declaration] 70 | void *addr = kmap_local_page(page + i); | ^ mm/mempool.c:70:17: note: did you mean 'kmap_to_page'? ./include/linux/highmem.h:124:14: note: 'kmap_to_page' declared here 124 | struct page *kmap_to_page(void *addr); | ^ mm/mempool.c:70:10: error: incompatible integer to pointer conversion initializing 'void *' with an expression of type 'int' [-Wint-conversion] 70 | void *addr = kmap_local_page(page + i); | ^ ~~~~~~~~~~~~~~~~~~~~~~~~~ mm/mempool.c:73:4: error: implicit declaration of function 'kunmap_local' [-Werror,-Wimplicit-function-declaration] 73 | kunmap_local(addr); | ^ mm/mempool.c:101:8: warning: GCC does not allow variable declarations in for loop initializers before C99 [-Wgcc-compat] 101 | for (int i = 0; i < (1 << order); i++) { | ^ mm/mempool.c:103:17: error: implicit declaration of function 'kmap_local_page' [-Werror,-Wimplicit-function-declaration] 103 | void *addr = kmap_local_page(page + i); | ^ mm/mempool.c:103:10: error: incompatible integer to pointer conversion initializing 'void *' with an expression of type 'int' [-Wint-conversion] 103 | void *addr = kmap_local_page(page + i); | ^ ~~~~~~~~~~~~~~~~~~~~~~~~~ mm/mempool.c:106:4: error: implicit declaration of function 'kunmap_local' [-Werror,-Wimplicit-function-declaration] 106 | kunmap_local(addr); | ^ CC fs/notify/fanotify/fanotify.o 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-69286cb5f5b8743b... - dashboard: https://d.kernelci.org/build/maestro:69286cb5f5b8743b1f65f372

## i386_defconfig+allmodconfig+CONFIG_FRAME_WARN=2048 on (i386): - compiler: clang-21 - config: https://files.kernelci.org/kbuild-clang-21-i386-allmodconfig-69286ceff5b8743... - dashboard: https://d.kernelci.org/build/maestro:69286ceff5b8743b1f65f3b6

#kernelci issue maestro:edfc0791be4ae7547a2a17054e9cd0317c106f20

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