|author||Andi Kleen <email@example.com>||2009-09-16 11:50:15 +0200|
|committer||Andi Kleen <firstname.lastname@example.org>||2009-09-16 11:50:15 +0200|
HWPOISON: The high level memory error handler in the VM v7
Add the high level memory handler that poisons pages that got corrupted by hardware (typically by a two bit flip in a DIMM or a cache) on the Linux level. The goal is to prevent everyone from accessing these pages in the future. This done at the VM level by marking a page hwpoisoned and doing the appropriate action based on the type of page it is. The code that does this is portable and lives in mm/memory-failure.c To quote the overview comment: High level machine check handler. Handles pages reported by the hardware as being corrupted usually due to a 2bit ECC memory or cache failure. This focuses on pages detected as corrupted in the background. When the current CPU tries to consume corruption the currently running process can just be killed directly instead. This implies that if the error cannot be handled for some reason it's safe to just ignore it because no corruption has been consumed yet. Instead when that happens another machine check will happen. Handles page cache pages in various states. The tricky part here is that we can access any page asynchronous to other VM users, because memory failures could happen anytime and anywhere, possibly violating some of their assumptions. This is why this code has to be extremely careful. Generally it tries to use normal locking rules, as in get the standard locks, even if that means the error handling takes potentially a long time. Some of the operations here are somewhat inefficient and have non linear algorithmic complexity, because the data structures have not been optimized for this case. This is in particular the case for the mapping from a vma to a process. Since this case is expected to be rare we hope we can get away with this. There are in principle two strategies to kill processes on poison: - just unmap the data and wait for an actual reference before killing - kill as soon as corruption is detected. Both have advantages and disadvantages and should be used in different situations. Right now both are implemented and can be switched with a new sysctl vm.memory_failure_early_kill The default is early kill. The patch does some rmap data structure walking on its own to collect processes to kill. This is unusual because normally all rmap data structure knowledge is in rmap.c only. I put it here for now to keep everything together and rmap knowledge has been seeping out anyways Includes contributions from Johannes Weiner, Chris Mason, Fengguang Wu, Nick Piggin (who did a lot of great work) and others. Cc: email@example.com Cc: firstname.lastname@example.org Signed-off-by: Andi Kleen <email@example.com> Acked-by: Rik van Riel <firstname.lastname@example.org> Reviewed-by: Hidehiro Kawai <email@example.com>
Diffstat (limited to 'mm/Kconfig')
1 files changed, 10 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index 3aa519f52e1..ea2d8b61c63 100644
@@ -233,6 +233,16 @@ config DEFAULT_MMAP_MIN_ADDR
+ depends on MMU
+ depends on X86_MCE
+ bool "Enable recovery from hardware memory errors"
+ Enables code to recover from some memory failures on systems
+ with MCA recovery. This allows a system to continue running
+ even when some of its memory has uncorrected errors. This requires
+ special hardware support and typically ECC memory.
int "Turn on mmap() excess space trimming before booting"
depends on !MMU