By default ARCH_SLAB_MINALIGN is defined in "include/linux/slab.h" as "__alignof__(unsigned long long)" which looks fine but not for ARC. ARC tools ABI sets align of "long long" the same as for "long" = 4 instead of 8 one may think of. Thus slab allocator may easily allocate a buffer which is 32-bit aligned. And most of the time it's OK until we start dealing with 64-bit atomics with special LLOCKD/SCONDD instructions which (as opposed to their 32-bit counterparts LLOCK/SCOND) operate with full 64-bit words but those words must be 64-bit aligned. Fixes Ext4 folder removal: --------------------->8------------------- [ 4.015732] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null) [ 4.167881] [ 4.167881] Misaligned Access [ 4.172356] Path: /bin/busybox.nosuid [ 4.176004] CPU: 2 PID: 171 Comm: rm Not tainted 4.19.14-yocto-standard #1 [ 4.182851] [ 4.182851] [ECR ]: 0x000d0000 => Check Programmer's Manual [ 4.190061] [EFA ]: 0xbeaec3fc [ 4.190061] [BLINK ]: ext4_delete_entry+0x210/0x234 [ 4.190061] [ERET ]: ext4_delete_entry+0x13e/0x234 [ 4.202985] [STAT32]: 0x80080002 : IE K [ 4.207236] BTA: 0x9009329c SP: 0xbe5b1ec4 FP: 0x00000000 [ 4.212790] LPS: 0x9074b118 LPE: 0x9074b120 LPC: 0x00000000 [ 4.218348] r00: 0x00000040 r01: 0x00000021 r02: 0x00000001 [ 4.218348] r03: 0x00000000 r04: 0x00000002 r05: 0x00000000 [ 4.218348] r06: 0x000000c6 r07: 0x00000000 r08: 0x9050f140 [ 4.218348] r09: 0x000000c6 r10: 0x0000000a r11: 0x00000000 [ 4.218348] r12: 0x90247a9c r13: 0x9004e574 r14: 0x0008e150 [ 4.218348] r15: 0x000989b8 r16: 0x0008cbec r17: 0x0009806c [ 4.218348] r18: 0x0009806c r19: 0x0008e150 r20: 0x0008f0f8 [ 4.218348] r21: 0x000000ab r22: 0x0008f0f8 r23: 0x00000000 [ 4.218348] r24: 0x00000000 r25: 0x00000000 [ 4.218348] [ 4.218348] [ 4.270510] [ 4.270510] Stack Trace: [ 4.274510] ext4_delete_entry+0x13e/0x234 [ 4.278695] ext4_rmdir+0xe0/0x238 [ 4.282187] vfs_rmdir+0x50/0xf0 [ 4.285492] do_rmdir+0x9e/0x154 [ 4.288802] EV_Trap+0x110/0x114 --------------------->8------------------- Signed-off-by: Alexey Brodkin <abrodkin@xxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # 4.8+ --- arch/arc/include/asm/cache.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/arc/include/asm/cache.h b/arch/arc/include/asm/cache.h index f393b663413e..74f8fcaaef5c 100644 --- a/arch/arc/include/asm/cache.h +++ b/arch/arc/include/asm/cache.h @@ -52,6 +52,16 @@ #define cache_line_size() SMP_CACHE_BYTES #define ARCH_DMA_MINALIGN SMP_CACHE_BYTES +/* + * Make sure slab-allocated buffers are 64-bit aligned. + * This is required for llockd/scondd to deal with 64-bit aligned dwords. + * By default ARCH_SLAB_MINALIGN is __alignof__(long long) which in + * case of ARC is 4 instead of 8! + */ +#ifdef CONFIG_ARC_HAS_LL64 +#define ARCH_SLAB_MINALIGN 8 +#endif + extern void arc_cache_init(void); extern char *arc_cache_mumbojumbo(int cpu_id, char *buf, int len); extern void read_decode_cache_bcr(void); -- 2.16.2
