# git rev-parse -q --verify 981ee95cc1f5905ae4936b0dd501085909cdc14f^{commit} 981ee95cc1f5905ae4936b0dd501085909cdc14f already have revision, skipping fetch # git checkout -q -f -B kisskb 981ee95cc1f5905ae4936b0dd501085909cdc14f # git clean -qxdf # < git log -1 # commit 981ee95cc1f5905ae4936b0dd501085909cdc14f # Author: Mateusz Guzik # Date: Wed Jan 25 16:55:57 2023 +0100 # # vfs: avoid duplicating creds in faccessat if possible # # access(2) remains commonly used, for example on exec: # access("/etc/ld.so.preload", R_OK) # # or when running gcc: strace -c gcc empty.c # # % time seconds usecs/call calls errors syscall # ------ ----------- ----------- --------- --------- ---------------- # 0.00 0.000000 0 42 26 access # # It falls down to do_faccessat without the AT_EACCESS flag, which in turn # results in allocation of new creds in order to modify fsuid/fsgid and # caps. This is a very expensive process single-threaded and most notably # multi-threaded, with numerous structures getting refed and unrefed on # imminent new cred destruction. # # Turns out for typical consumers the resulting creds would be identical # and this can be checked upfront, avoiding the hard work. # # An access benchmark plugged into will-it-scale running on Cascade Lake # shows: # # test proc before after # access1 1 1310582 2908735 (+121%) # distinct files # access1 24 4716491 63822173 (+1353%) # distinct files # access2 24 2378041 5370335 (+125%) # same file # # The above benchmarks are not integrated into will-it-scale, but can be # found in a pull request: # # https://github.com/antonblanchard/will-it-scale/pull/36/files # # Signed-off-by: Mateusz Guzik # Cc: Al Viro # Signed-off-by: Linus Torvalds # < /opt/cross/kisskb/korg/gcc-8.5.0-nolibc/m68k-linux/bin/m68k-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-8.5.0-nolibc/m68k-linux/bin/m68k-linux-ld --version # < git log --format=%s --max-count=1 981ee95cc1f5905ae4936b0dd501085909cdc14f # < make -s -j 160 ARCH=m68k O=/kisskb/build/linus_m68k-allmodconfig_m68k-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.5.0-nolibc/m68k-linux/bin/m68k-linux- allmodconfig # Added to kconfig CONFIG_BUILD_DOCSRC=n # Added to kconfig CONFIG_MODULE_SIG=n # Added to kconfig CONFIG_SAMPLES=n # < make -s -j 160 ARCH=m68k O=/kisskb/build/linus_m68k-allmodconfig_m68k-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.5.0-nolibc/m68k-linux/bin/m68k-linux- help # make -s -j 160 ARCH=m68k O=/kisskb/build/linus_m68k-allmodconfig_m68k-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.5.0-nolibc/m68k-linux/bin/m68k-linux- olddefconfig # make -s -j 160 ARCH=m68k O=/kisskb/build/linus_m68k-allmodconfig_m68k-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.5.0-nolibc/m68k-linux/bin/m68k-linux- /kisskb/src/drivers/media/i2c/imx290.c:1090:12: error: 'imx290_runtime_suspend' defined but not used [-Werror=unused-function] static int imx290_runtime_suspend(struct device *dev) ^~~~~~~~~~~~~~~~~~~~~~ /kisskb/src/drivers/media/i2c/imx290.c:1082:12: error: 'imx290_runtime_resume' defined but not used [-Werror=unused-function] static int imx290_runtime_resume(struct device *dev) ^~~~~~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors make[5]: *** [/kisskb/src/scripts/Makefile.build:252: drivers/media/i2c/imx290.o] Error 1 make[5]: *** Waiting for unfinished jobs.... make[4]: *** [/kisskb/src/scripts/Makefile.build:494: drivers/media/i2c] Error 2 make[4]: *** Waiting for unfinished jobs.... /kisskb/src/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c: In function 'mxc_jpeg_dec_irq': /kisskb/src/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c:641:28: error: array subscript 2 is above array bounds of 'u32[2]' {aka 'unsigned int[2]'} [-Werror=array-bounds] size += q_data->sizeimage[i]; ~~~~~~~~~~~~~~~~~^~~ /kisskb/src/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c:641:28: error: array subscript 3 is above array bounds of 'u32[2]' {aka 'unsigned int[2]'} [-Werror=array-bounds] cc1: all warnings being treated as errors make[7]: *** [/kisskb/src/scripts/Makefile.build:252: drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.o] Error 1 make[6]: *** [/kisskb/src/scripts/Makefile.build:494: drivers/media/platform/nxp/imx-jpeg] Error 2 make[5]: *** [/kisskb/src/scripts/Makefile.build:494: drivers/media/platform/nxp] Error 2 make[5]: *** Waiting for unfinished jobs.... make[4]: *** [/kisskb/src/scripts/Makefile.build:494: drivers/media/platform] Error 2 make[3]: *** [/kisskb/src/scripts/Makefile.build:494: drivers/media] Error 2 make[3]: *** Waiting for unfinished jobs.... make[2]: *** [/kisskb/src/scripts/Makefile.build:494: drivers] Error 2 make[2]: *** Waiting for unfinished jobs.... make[1]: *** [/kisskb/src/Makefile:2028: .] Error 2 make: *** [Makefile:226: __sub-make] Error 2 Command 'make -s -j 160 ARCH=m68k O=/kisskb/build/linus_m68k-allmodconfig_m68k-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.5.0-nolibc/m68k-linux/bin/m68k-linux- ' returned non-zero exit status 2 # rm -rf /kisskb/build/linus_m68k-allmodconfig_m68k-gcc8 # Build took: 0:07:34.071122