Memory hot unplug on PowerNV radix hosts is broken. Our memory block size is 256MB but since we map the linear region with very large pages, each pte we tear down maps 1GB. A hot unplug of one 256MB memory block results in 768MB of memory getting unintentionally unmapped. At this point we are likely to oops. Fix this by increasing our memory block size to 1GB on PowerNV radix hosts.
Unified · Split
| @@ -272,7 +272,15 @@ static void pnv_kexec_cpu_down(int crash_shutdown, int secondary) · 271 unmodified lines | |||
| 272 | #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE | 272 | #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE |
| 273 | static unsigned long pnv_memory_block_size(void) | 273 | static unsigned long pnv_memory_block_size(void) |
| 274 | { | 274 | { |
| 275 | return 256UL * 1024 * 1024; | 275 | /* |
| 276 | * We map the kernel linear region with 1GB large pages on radix. For | ||
| 277 | * memory hot unplug to work our memory block size must be at least | ||
| 278 | * this size. | ||
| 279 | */ | ||
| 280 | if (radix_enabled()) | ||
| 281 | return 1UL * 1024 * 1024 * 1024; | ||
| 282 | else | ||
| 283 | return 256UL * 1024 * 1024; | ||
| 276 | } | 284 | } |
| 277 | #endif | 285 | #endif |
| 278 | 286 | ||