4.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michael Ellerman <mpe@xxxxxxxxxxxxxx> commit 4749228f022893faf54a3dbc70796f78b7d4f342 upstream. In crc32c_vpmsum() we call enable_kernel_altivec() without first disabling preemption, which is not allowed: WARNING: CPU: 9 PID: 2949 at ../arch/powerpc/kernel/process.c:277 enable_kernel_altivec+0x100/0x120 Modules linked in: dm_thin_pool dm_persistent_data dm_bio_prison dm_bufio libcrc32c vmx_crypto ... CPU: 9 PID: 2949 Comm: docker Not tainted 4.11.0-rc5-compiler_gcc-6.3.1-00033-g308ac7563944 #381 ... NIP [c00000000001e320] enable_kernel_altivec+0x100/0x120 LR [d000000003df0910] crc32c_vpmsum+0x108/0x150 [crc32c_vpmsum] Call Trace: 0xc138fd09 (unreliable) crc32c_vpmsum+0x108/0x150 [crc32c_vpmsum] crc32c_vpmsum_update+0x3c/0x60 [crc32c_vpmsum] crypto_shash_update+0x88/0x1c0 crc32c+0x64/0x90 [libcrc32c] dm_bm_checksum+0x48/0x80 [dm_persistent_data] sb_check+0x84/0x120 [dm_thin_pool] dm_bm_validate_buffer.isra.0+0xc0/0x1b0 [dm_persistent_data] dm_bm_read_lock+0x80/0xf0 [dm_persistent_data] __create_persistent_data_objects+0x16c/0x810 [dm_thin_pool] dm_pool_metadata_open+0xb0/0x1a0 [dm_thin_pool] pool_ctr+0x4cc/0xb60 [dm_thin_pool] dm_table_add_target+0x16c/0x3c0 table_load+0x184/0x400 ctl_ioctl+0x2f0/0x560 dm_ctl_ioctl+0x38/0x50 do_vfs_ioctl+0xd8/0x920 SyS_ioctl+0x68/0xc0 system_call+0x38/0xfc It used to be sufficient just to call pagefault_disable(), because that also disabled preemption. But the two were decoupled in commit 8222dbe21e79 ("sched/preempt, mm/fault: Decouple preemption from the page fault logic") in mid 2015. So add the missing preempt_disable/enable(). We should also call disable_kernel_fp(), although it does nothing by default, there is a debug switch to make it active and all enables should be paired with disables. Fixes: 6dd7a82cc54e ("crypto: powerpc - Add POWER8 optimised crc32c") Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/powerpc/crypto/crc32c-vpmsum_glue.c | 3 +++ 1 file changed, 3 insertions(+) --- a/arch/powerpc/crypto/crc32c-vpmsum_glue.c +++ b/arch/powerpc/crypto/crc32c-vpmsum_glue.c @@ -33,10 +33,13 @@ static u32 crc32c_vpmsum(u32 crc, unsign } if (len & ~VMX_ALIGN_MASK) { + preempt_disable(); pagefault_disable(); enable_kernel_altivec(); crc = __crc32c_vpmsum(crc, p, len & ~VMX_ALIGN_MASK); + disable_kernel_altivec(); pagefault_enable(); + preempt_enable(); } tail = len & VMX_ALIGN_MASK;