# git rev-parse -q --verify 66be4e66a7f422128748e3c3ef6ee72b20a6197b^{commit} 66be4e66a7f422128748e3c3ef6ee72b20a6197b already have revision, skipping fetch # git checkout -q -f -B kisskb 66be4e66a7f422128748e3c3ef6ee72b20a6197b # git clean -qxdf # < git log -1 # commit 66be4e66a7f422128748e3c3ef6ee72b20a6197b # Author: Linus Torvalds # Date: Mon Jun 3 13:26:20 2019 -0700 # # rcu: locking and unlocking need to always be at least barriers # # Herbert Xu pointed out that commit bb73c52bad36 ("rcu: Don't disable # preemption for Tiny and Tree RCU readers") was incorrect in making the # preempt_disable/enable() be conditional on CONFIG_PREEMPT_COUNT. # # If CONFIG_PREEMPT_COUNT isn't enabled, the preemption enable/disable is # a no-op, but still is a compiler barrier. # # And RCU locking still _needs_ that compiler barrier. # # It is simply fundamentally not true that RCU locking would be a complete # no-op: we still need to guarantee (for example) that things that can # trap and cause preemption cannot migrate into the RCU locked region. # # The way we do that is by making it a barrier. # # See for example commit 386afc91144b ("spinlocks and preemption points # need to be at least compiler barriers") from back in 2013 that had # similar issues with spinlocks that become no-ops on UP: they must still # constrain the compiler from moving other operations into the critical # region. # # Now, it is true that a lot of RCU operations already use READ_ONCE() and # WRITE_ONCE() (which in practice likely would never be re-ordered wrt # anything remotely interesting), but it is also true that that is not # globally the case, and that it's not even necessarily always possible # (ie bitfields etc). # # Reported-by: Herbert Xu # Fixes: bb73c52bad36 ("rcu: Don't disable preemption for Tiny and Tree RCU readers") # Cc: stable@kernel.org # Cc: Boqun Feng # Cc: Paul E. McKenney # Signed-off-by: Linus Torvalds # < /opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-gcc --version # < /opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-ld --version # < git log --format=%s --max-count=1 66be4e66a7f422128748e3c3ef6ee72b20a6197b # < make -s -j 48 ARCH=powerpc O=/kisskb/build/linus_mpc85xx_defconfig_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- mpc85xx_defconfig # make -s -j 48 ARCH=powerpc O=/kisskb/build/linus_mpc85xx_defconfig_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- /kisskb/src/fs/proc/inode.c: In function 'proc_reg_open': /kisskb/src/include/linux/list.h:65:12: warning: 'pdeo' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/proc/inode.c:331:21: note: 'pdeo' was declared here /kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl': /kisskb/src/kernel/printk/printk.c:194:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/mm/hugetlb.c: In function 'alloc_pool_huge_page': /kisskb/src/mm/hugetlb.c:1465:5: warning: 'page' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/udf/unicode.c: In function 'udf_name_conv_char': /kisskb/src/fs/udf/unicode.c:132:8: warning: 'c' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/sound/soc/codecs/wm8960.c: In function 'wm8960_configure_clocking': /kisskb/src/sound/soc/codecs/wm8960.c:803:70: warning: 'j' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/sound/soc/codecs/wm8960.c:800:68: warning: 'i' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/base/regmap/regmap.c: In function 'regmap_raw_read': /kisskb/src/drivers/base/regmap/regmap.c:2589:6: warning: 'ret' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/base/regmap/regmap.c: In function '_regmap_raw_write': /kisskb/src/drivers/base/regmap/regmap.c:1850:6: warning: 'ret' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/ethernet/freescale/fs_enet/mac-scc.c: In function 'allocate_bd': /kisskb/src/drivers/net/ethernet/freescale/fs_enet/mac-scc.c:139:6: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] /kisskb/src/drivers/tty/serial/8250/8250_core.c: In function 'univ8250_release_irq': /kisskb/src/drivers/tty/serial/8250/8250_core.c:247:18: warning: 'i' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/tty/serial/8250/8250_core.c:227:19: note: 'i' was declared here /kisskb/src/arch/powerpc/boot/dts/fsl/mpc8555cds.dts:330.3-21: Warning (pci_device_bus_num): /pci@e0008000/i8259@19000:bus-range: PCI bus number 1 out of range, expected (0 - 0) /kisskb/src/arch/powerpc/boot/dts/fsl/mpc8541cds.dts:330.3-21: Warning (pci_device_bus_num): /pci@e0008000/i8259@19000:bus-range: PCI bus number 1 out of range, expected (0 - 0) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbdd200) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) INFO: Uncompressed kernel (size 0xbcca38) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0xc00000) Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:29 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5717888 Bytes = 5583.88 KiB = 5.45 MiB Load Address: 00000000 Entry Point: 00000000 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:30 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5748889 Bytes = 5614.15 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002a8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:30 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5748909 Bytes = 5614.17 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002e8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:30 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5750601 Bytes = 5615.82 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002a8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:30 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5748917 Bytes = 5614.18 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002a8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:30 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5748878 Bytes = 5614.14 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002e8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:31 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5749160 Bytes = 5614.41 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002e8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:31 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5749287 Bytes = 5614.54 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002a8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:31 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5750504 Bytes = 5615.73 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002a8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:31 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5749137 Bytes = 5614.39 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002a8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:31 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5749373 Bytes = 5614.62 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002a8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:31 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5749248 Bytes = 5614.50 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002e8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:31 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5748908 Bytes = 5614.17 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002e8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:31 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5749135 Bytes = 5614.39 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002a8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:31 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5749313 Bytes = 5614.56 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002a8 Image Name: Linux-5.2.0-rc3-g66be4e66a7f4 Created: Tue Jun 4 07:18:31 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 5749761 Bytes = 5615.00 KiB = 5.48 MiB Load Address: 00c00000 Entry Point: 00c002a8 Completed OK # rm -rf /kisskb/build/linus_mpc85xx_defconfig_powerpc-gcc4.6 # Build took: 0:01:34.458038