# git rev-parse -q --verify ba25b5ebe96a63940a12d9f8d73edebfcaad470c^{commit} ba25b5ebe96a63940a12d9f8d73edebfcaad470c already have revision, skipping fetch # git checkout -q -f -B kisskb ba25b5ebe96a63940a12d9f8d73edebfcaad470c # git clean -qxdf # < git log -1 # commit ba25b5ebe96a63940a12d9f8d73edebfcaad470c # Author: Aneesh Kumar K.V # Date: Fri Mar 13 15:18:42 2020 +0530 # # powerpc/hash64/devmap: Use H_PAGE_THP_HUGE when setting up huge devmap PTE entries # # H_PAGE_THP_HUGE is used to differentiate between a THP hugepage and # hugetlb hugepage entries. The difference is WRT how we handle hash # fault on these address. THP address enables MPSS in segments. We want # to manage devmap hugepage entries similar to THP pt entries. Hence use # H_PAGE_THP_HUGE for devmap huge PTE entries. # # With current code while handling hash PTE fault, we do set is_thp = # true when finding devmap PTE huge PTE entries. # # Current code also does the below sequence we setting up huge devmap # entries. # # entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); # if (pfn_t_devmap(pfn)) # entry = pmd_mkdevmap(entry); # # In that case we would find both H_PAGE_THP_HUGE and PAGE_DEVMAP set # for huge devmap PTE entries. This results in false positive error like # below. # # kernel BUG at /home/kvaneesh/src/linux/mm/memory.c:4321! # Oops: Exception in kernel mode, sig: 5 [#1] # LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries # Modules linked in: # CPU: 56 PID: 67996 Comm: t_mmap_dio Not tainted 5.6.0-rc4-59640-g371c804dedbc #128 # .... # NIP [c00000000044c9e4] __follow_pte_pmd+0x264/0x900 # LR [c0000000005d45f8] dax_writeback_one+0x1a8/0x740 # Call Trace: # str_spec.74809+0x22ffb4/0x2d116c (unreliable) # dax_writeback_one+0x1a8/0x740 # dax_writeback_mapping_range+0x26c/0x700 # ext4_dax_writepages+0x150/0x5a0 # do_writepages+0x68/0x180 # __filemap_fdatawrite_range+0x138/0x180 # file_write_and_wait_range+0xa4/0x110 # ext4_sync_file+0x370/0x6e0 # vfs_fsync_range+0x70/0xf0 # sys_msync+0x220/0x2e0 # system_call+0x5c/0x68 # # This is because our pmd_trans_huge check doesn't exclude _PAGE_DEVMAP. # # To make this all consistent, update pmd_mkdevmap to set # H_PAGE_THP_HUGE and pmd_trans_huge check now excludes _PAGE_DEVMAP # correctly. # # Fixes: ebd31197931d ("powerpc/mm: Add devmap support for ppc64") # Cc: stable@vger.kernel.org # v4.13+ # Signed-off-by: Aneesh Kumar K.V # Signed-off-by: Michael Ellerman # Link: https://lore.kernel.org/r/20200313094842.351830-1-aneesh.kumar@linux.ibm.com # < /opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux-gcc --version # < /opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux-ld --version # < git log --format=%s --max-count=1 ba25b5ebe96a63940a12d9f8d73edebfcaad470c # < make -s -j 32 ARCH=i386 O=/kisskb/build/powerpc-next_i386-allnoconfig_i386-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux- allnoconfig # < make -s -j 32 ARCH=i386 O=/kisskb/build/powerpc-next_i386-allnoconfig_i386-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux- help # make -s -j 32 ARCH=i386 O=/kisskb/build/powerpc-next_i386-allnoconfig_i386-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux- olddefconfig # make -s -j 32 ARCH=i386 O=/kisskb/build/powerpc-next_i386-allnoconfig_i386-gcc4.6 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux- /kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl': /kisskb/src/kernel/printk/printk.c:204:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/arch/x86/kernel/e820.c: In function 'e820__setup_pci_gap': /kisskb/src/arch/x86/kernel/e820.c:665:16: warning: 'gapstart' may be used uninitialized in this function [-Wuninitialized] Completed OK # rm -rf /kisskb/build/powerpc-next_i386-allnoconfig_i386-gcc4.6 # Build took: 0:00:20.480272