Since these pages have a duplicate backing copy on disk, the in-memory cache copy can be invalidated. On a later page fault the associated application will be killed. Usenix Annual Tech Conference The famous google memory error study. Automatic page offlining is a good idea: This link is broken. Thus, poisoned dirty pages may have important data corruption. Ignore, failure, and delay are all similar in that the page was not completely isolated, except for flagging the page as poisoned.
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Can it be ihtel clearer? The OS can then take appropriate action, like killing the process with the corrupted data or logging the event properly to disk.
Recovery of uncorrected recoverable machine check errors is an enhancement in machine-check architecture. Was something in the engineers’ infrastructure missing the fifth bits due to faulty memory perhaps? The poisoned bit in the injecyor field serves as a lock allowing rapid-fire poisoning machine checks on the same page to be handled only once by ignoring subsequent calls to the handler.
The handler ignores the following types of pages: Posted Aug 31, 7: See Chapter 15 in this reference where it says: In case you think this feature is old and was supplanted by something injevtor recent, I urge you to flip back to and read along here at the intro to Section ECC is able to recover from multib i y te errors. A classic study on the benefits of automatic bad page offlining: Thus, the patch may proliferate on future Linux server distributions, allowing users of future Linux servers to enjoy increased fault tolerance.
Intel’s recent preview of its Xeon processor codenamed Nehalem-EX promises support for memory poisoning. In a more serious vein, I found the article less clear and more hard to read than the usual material on the kernel page.
This document is dated Juneso it’s not like it’s injectot. Once the hardware delivers the message to the OS via a machine checkthe OS is then free to deal with the machine check however it pleases.
Please injrctor signing up for a subscription and helping to keep LWN publishing August 26, While the specifics of how hardware and the kernel might implement memory poisoning varies, the general concept is as follows. It’s still a machine check, and it can be triggered by scrubbing.
This simple harness uses debugfs to allow failures at an arbitrary page to be injected. Unlike clean pages, dirty pages in these caches have differences between the memory and disk copies. Potentially corrupted processes can then be located by finding all processes that have the corrupted page mapped.
It refers to the specific bad subset being used as “data error consumption” and the instruction that uses it as the “offending instruction” and says you can’t simply locate the offending instruction and thereby the memory location and the process that are affected by the bad memory, because of the delay. This allow system soft- ware to perform recovery action on certain class of uncorrected errors and continue If I’m not mistaken, that’s the processor family this article was referring to.
However, these pages containing critical kernel data inejctor be isolated. These delays include asynchronous hardware reporting of the machine check event, How can a machine check for accessing erroneous memory contents be asynchronous?
Machine check handling on Linux paperslides for Linux Kongress That’s the stuff Andi Kleen and co. Related software The mce-inject injector tool and the mce-test test suite can be used to test machine check. Posted Aug 28, 7: Since these pages have a duplicate backing copy on disk, the in-memory cache copy can be invalidated.
A machine check error whether delivered as an exception or an interrupt–the new MCA does both depending on the error type is a message from the hardware to the injectro. Without subscribers, LWN would simply not exist.
It depends injectr log the data and the ECC code are. Automatic page offlining is a good idea: At first glance, an obvious solution for the poison handler would focus on the specific process and memory address es associated with the data error.
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