Buildresult: linus/skiroot_defconfig/powerpc-gcc5 built on Feb 18 2022, 05:36

kisskb

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Status:	Failed
Date/Time:	Feb 18 2022, 05:36
Duration:	0:01:41.215971
Builder:	ka2
Revision:	mm: don't try to NUMA-migrate COW pages that have other uses (`80d47f5de5e311cbc0d01ebb6ee684e8f4c196c6)`
Target:	linus/skiroot_defconfig/powerpc-gcc5
Branch:	linus
Compiler:	powerpc-gcc5 (powerpc64-linux-gcc (GCC) 5.5.0 / GNU ld (GNU Binutils) 2.29.1.20170915)
Config:	skiroot_defconfig (download)
Log:	Download original Possible errors arch/powerpc/kernel/stacktrace.c:171:2: error: implicit declaration of function 'nmi_cpu_backtrace' [-Werror=implicit-function-declaration] arch/powerpc/kernel/stacktrace.c:226:2: error: implicit declaration of function 'nmi_trigger_cpumask_backtrace' [-Werror=implicit-function-declaration] cc1: all warnings being treated as errors make[3]: * [scripts/Makefile.build:288: arch/powerpc/kernel/stacktrace.o] Error 1 make[2]: * [scripts/Makefile.build:550: arch/powerpc/kernel] Error 2 make[1]: * [Makefile:1831: arch/powerpc] Error 2 make: * [Makefile:219: __sub-make] Error 2 No warnings found in log. Full Log # git rev-parse -q --verify 80d47f5de5e311cbc0d01ebb6ee684e8f4c196c6^{commit} 80d47f5de5e311cbc0d01ebb6ee684e8f4c196c6 already have revision, skipping fetch # git checkout -q -f -B kisskb 80d47f5de5e311cbc0d01ebb6ee684e8f4c196c6 # git clean -qxdf # < git log -1 # commit 80d47f5de5e311cbc0d01ebb6ee684e8f4c196c6 # Author: Linus Torvalds <torvalds@linux-foundation.org> # Date: Thu Feb 17 08:57:47 2022 -0800 # # mm: don't try to NUMA-migrate COW pages that have other uses # # Oded Gabbay reports that enabling NUMA balancing causes corruption with # his Gaudi accelerator test load: # # "All the details are in the bug, but the bottom line is that somehow, # this patch causes corruption when the numa balancing feature is # enabled AND we don't use process affinity AND we use GUP to pin pages # so our accelerator can DMA to/from system memory. # # Either disabling numa balancing, using process affinity to bind to # specific numa-node or reverting this patch causes the bug to # disappear" # # and Oded bisected the issue to commit 09854ba94c6a ("mm: do_wp_page() # simplification"). # # Now, the NUMA balancing shouldn't actually be changing the writability # of a page, and as such shouldn't matter for COW. But it appears it # does. Suspicious. # # However, regardless of that, the condition for enabling NUMA faults in # change_pte_range() is nonsensical. It uses "page_mapcount(page)" to # decide if a COW page should be NUMA-protected or not, and that makes # absolutely no sense. # # The number of mappings a page has is irrelevant: not only does GUP get a # reference to a page as in Oded's case, but the other mappings migth be # paged out and the only reference to them would be in the page count. # # Since we should never try to NUMA-balance a page that we can't move # anyway due to other references, just fix the code to use 'page_count()'. # Oded confirms that that fixes his issue. # # Now, this does imply that something in NUMA balancing ends up changing # page protections (other than the obvious one of making the page # inaccessible to get the NUMA faulting information). Otherwise the COW # simplification wouldn't matter - since doing the GUP on the page would # make sure it's writable. # # The cause of that permission change would be good to figure out too, # since it clearly results in spurious COW events - but fixing the # nonsensical test that just happened to work before is obviously the # CorrectThing(tm) to do regardless. # # Fixes: 09854ba94c6a ("mm: do_wp_page() simplification") # Link: https://bugzilla.kernel.org/show_bug.cgi?id=215616 # Link: https://lore.kernel.org/all/CAFCwf10eNmwq2wD71xjUhqkvv5+_pJMR1nPug2RqNDcFT4H86Q@mail.gmail.com/ # Reported-and-tested-by: Oded Gabbay <oded.gabbay@gmail.com> # Cc: David Hildenbrand <david@redhat.com> # Cc: Peter Xu <peterx@redhat.com> # Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version # < git log --format=%s --max-count=1 80d47f5de5e311cbc0d01ebb6ee684e8f4c196c6 # < make -s -j 48 ARCH=powerpc O=/kisskb/build/linus_skiroot_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- skiroot_defconfig # < make -s -j 48 ARCH=powerpc O=/kisskb/build/linus_skiroot_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- help # make -s -j 48 ARCH=powerpc O=/kisskb/build/linus_skiroot_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- olddefconfig # make -s -j 48 ARCH=powerpc O=/kisskb/build/linus_skiroot_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- /kisskb/src/arch/powerpc/kernel/stacktrace.c: In function 'handle_backtrace_ipi': /kisskb/src/arch/powerpc/kernel/stacktrace.c:171:2: error: implicit declaration of function 'nmi_cpu_backtrace' [-Werror=implicit-function-declaration] nmi_cpu_backtrace(regs); ^ /kisskb/src/arch/powerpc/kernel/stacktrace.c: In function 'arch_trigger_cpumask_backtrace': /kisskb/src/arch/powerpc/kernel/stacktrace.c:226:2: error: implicit declaration of function 'nmi_trigger_cpumask_backtrace' [-Werror=implicit-function-declaration] nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace_ipi); ^ cc1: all warnings being treated as errors make[3]: * [/kisskb/src/scripts/Makefile.build:288: arch/powerpc/kernel/stacktrace.o] Error 1 make[3]: * Waiting for unfinished jobs.... make[2]: * [/kisskb/src/scripts/Makefile.build:550: arch/powerpc/kernel] Error 2 make[2]: * Waiting for unfinished jobs.... make[1]: * [/kisskb/src/Makefile:1831: arch/powerpc] Error 2 make[1]: * Waiting for unfinished jobs.... make: *** [Makefile:219: __sub-make] Error 2 Command 'make -s -j 48 ARCH=powerpc O=/kisskb/build/linus_skiroot_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- ' returned non-zero exit status 2 # rm -rf /kisskb/build/linus_skiroot_defconfig_powerpc-gcc5 # Build took: 0:01:41.215971

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