# git rev-parse -q --verify f41c880e164dc3c9fc3eff6ed27e97583af41986^{commit} f41c880e164dc3c9fc3eff6ed27e97583af41986 already have revision, skipping fetch # git checkout -q -f -B kisskb f41c880e164dc3c9fc3eff6ed27e97583af41986 # git clean -qxdf # < git log -1 # commit f41c880e164dc3c9fc3eff6ed27e97583af41986 # Author: Nicholas Piggin # Date: Mon Jun 3 16:05:31 2019 +1000 # # powerpc/64s: Fix THP PMD collapse serialisation # # Commit 1b2443a547f9 ("powerpc/book3s64: Avoid multiple endian # conversion in pte helpers") changed the actual bitwise tests in # pte_access_permitted by using pte_write() and pte_present() helpers # rather than raw bitwise testing _PAGE_WRITE and _PAGE_PRESENT bits. # # The pte_present change now returns true for ptes which are # !_PAGE_PRESENT and _PAGE_INVALID, which is the combination used by # pmdp_invalidate to synchronize access from lock-free lookups. # pte_access_permitted is used by pmd_access_permitted, so allowing GUP # lock free access to proceed with such PTEs breaks this # synchronisation. # # This bug has been observed on HPT host, with random crashes and # corruption in guests, usually together with bad PMD messages in the # host. # # Fix this by adding an explicit check in pmd_access_permitted, and # documenting the condition explicitly. # # The pte_write() change should be okay, and would prevent GUP from # falling back to the slow path when encountering savedwrite ptes, which # matches what x86 (that does not implement savedwrite) does. # # Fixes: 1b2443a547f9 ("powerpc/book3s64: Avoid multiple endian conversion in pte helpers") # Cc: stable@vger.kernel.org # v4.20+ # Signed-off-by: Nicholas Piggin # Signed-off-by: Michael Ellerman # < /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 f41c880e164dc3c9fc3eff6ed27e97583af41986 # < make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- pseries_defconfig # make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig_powerpc-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- /kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl': /kisskb/src/kernel/printk/printk.c:193:16: 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:1464:5: warning: 'page' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/kernel/futex.c: In function 'do_futex': /kisskb/src/kernel/futex.c:1658:3: warning: 'oldval' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/kernel/futex.c:1633:6: note: 'oldval' was declared here /kisskb/src/net/bridge/br_netlink.c: In function 'br_afspec.isra.28': /kisskb/src/net/bridge/br_netlink.c:652:7: warning: 'err' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/core/devlink.c: In function 'devlink_fmsg_snd.constprop.72': /kisskb/src/net/core/devlink.c:4394:6: warning: 'err' 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/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/fs/nfsd/nfs4xdr.c: In function 'nfsd4_encode_components_esc': /kisskb/src/fs/nfsd/nfs4xdr.c:2077:9: warning: 'str' 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/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/drivers/net/tun.c: In function 'tun_get_user': /kisskb/src/drivers/net/tun.c:1851:30: warning: 'copylen' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/tun.c:1764:46: warning: 'linear' may be used uninitialized in this function [-Wuninitialized] WARNING: vmlinux.o(.text+0x362a): Section mismatch in reference from the variable start_here_multiplatform to the function .init.text:.early_setup() The function start_here_multiplatform() references the function __init .early_setup(). This is often because start_here_multiplatform lacks a __init annotation or the annotation of .early_setup is wrong. Completed OK # rm -rf /kisskb/build/powerpc-fixes_pseries_defconfig_powerpc-gcc4.6 # Build took: 0:02:16.153876