Messages in this thread | | | Subject | Re: [PATCH] mm: add config option to select the initial overcommit mode | From | "Austin S. Hemmelgarn" <> | Date | Fri, 13 May 2016 10:14:55 -0400 |
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On 2016-05-13 09:34, Sebastian Frias wrote: > Hi Austin, > > On 05/13/2016 03:11 PM, Austin S. Hemmelgarn wrote: >> On 2016-05-13 08:39, Sebastian Frias wrote: >>> >>> My point is that it seems to be possible to deal with such conditions in a more controlled way, ie: a way that is less random and less abrupt. >> There's an option for the OOM-killer to just kill the allocating task instead of using the scoring heuristic. This is about as deterministic as things can get though. > > By the way, why does it has to "kill" anything in that case? > I mean, shouldn't it just tell the allocating task that there's not enough memory by letting malloc return NULL? In theory, that's a great idea. In practice though, it only works if: 1. The allocating task correctly handles malloc() (or whatever other function it uses) returning NULL, which a number of programs don't. 2. The task actually has fallback options for memory limits. Many programs that do handle getting a NULL pointer from malloc() handle it by exiting anyway, so there's not as much value in this case. 3. There isn't a memory leak somewhere on the system. Killing the allocating task doesn't help much if this is the case of course.
You have to keep in mind though, that on a properly provisioned system, the only situations where the OOM killer should be invoked are when there's a memory leak, or when someone is intentionally trying to DoS the system through memory exhaustion. If you're hitting the OOM killer for any other reason than those or a kernel bug, then you just need more memory or more swap space.
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