path: root/mm/memtest.c
diff options
authorTony Luck <>2015-06-24 16:58:09 -0700
committerLinus Torvalds <>2015-06-24 17:49:44 -0700
commitfc6daaf93151877748f8096af6b3fddb147f22d6 (patch)
tree1892f34cca08d40af6598bccae87c42037c5ea80 /mm/memtest.c
parent6afdb859b71019143b8eecda02b8b29b03185055 (diff)
mm/memblock: add extra "flags" to memblock to allow selection of memory based on attribute
Some high end Intel Xeon systems report uncorrectable memory errors as a recoverable machine check. Linux has included code for some time to process these and just signal the affected processes (or even recover completely if the error was in a read only page that can be replaced by reading from disk). But we have no recovery path for errors encountered during kernel code execution. Except for some very specific cases were are unlikely to ever be able to recover. Enter memory mirroring. Actually 3rd generation of memory mirroing. Gen1: All memory is mirrored Pro: No s/w enabling - h/w just gets good data from other side of the mirror Con: Halves effective memory capacity available to OS/applications Gen2: Partial memory mirror - just mirror memory begind some memory controllers Pro: Keep more of the capacity Con: Nightmare to enable. Have to choose between allocating from mirrored memory for safety vs. NUMA local memory for performance Gen3: Address range partial memory mirror - some mirror on each memory controller Pro: Can tune the amount of mirror and keep NUMA performance Con: I have to write memory management code to implement The current plan is just to use mirrored memory for kernel allocations. This has been broken into two phases: 1) This patch series - find the mirrored memory, use it for boot time allocations 2) Wade into mm/page_alloc.c and define a ZONE_MIRROR to pick up the unused mirrored memory from mm/memblock.c and only give it out to select kernel allocations (this is still being scoped because page_alloc.c is scary). This patch (of 3): Add extra "flags" to memblock to allow selection of memory based on attribute. No functional changes Signed-off-by: Tony Luck <> Cc: Xishi Qiu <> Cc: Hanjun Guo <> Cc: Xiexiuqi <> Cc: Ingo Molnar <> Cc: Thomas Gleixner <> Cc: "H. Peter Anvin" <> Cc: Yinghai Lu <> Cc: Naoya Horiguchi <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/memtest.c')
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/memtest.c b/mm/memtest.c
index 1997d934b13b..0a1cc133f6d7 100644
--- a/mm/memtest.c
+++ b/mm/memtest.c
@@ -74,7 +74,8 @@ static void __init do_one_pass(u64 pattern, phys_addr_t start, phys_addr_t end)
u64 i;
phys_addr_t this_start, this_end;
- for_each_free_mem_range(i, NUMA_NO_NODE, &this_start, &this_end, NULL) {
+ for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &this_start,
+ &this_end, NULL) {
this_start = clamp(this_start, start, end);
this_end = clamp(this_end, start, end);
if (this_start < this_end) {