Messages in this thread | | | Subject | Re: [PATCH] mm: page_alloc: document kmemleak's non-blockable __GFP_NOFAIL case | From | Yang Shi <> | Date | Mon, 15 Jul 2019 10:00:34 -0700 |
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On 7/15/19 6:06 AM, Matthew Wilcox wrote: > On Sun, Jul 14, 2019 at 08:47:07PM -0700, Yang Shi wrote: >> >> On 7/13/19 2:25 PM, Matthew Wilcox wrote: >>> On Sat, Jul 13, 2019 at 04:49:04AM +0800, Yang Shi wrote: >>>> When running ltp's oom test with kmemleak enabled, the below warning was >>>> triggerred since kernel detects __GFP_NOFAIL & ~__GFP_DIRECT_RECLAIM is >>>> passed in: >>> There are lots of places where kmemleak will call kmalloc with >>> __GFP_NOFAIL and ~__GFP_DIRECT_RECLAIM (including the XArray code, which >>> is how I know about it). It needs to be fixed to allow its internal >>> allocations to fail and return failure of the original allocation as >>> a consequence. >> Do you mean kmemleak internal allocation? It would fail even though >> __GFP_NOFAIL is passed in if GFP_NOWAIT is specified. Currently buddy >> allocator will not retry if the allocation is non-blockable. > Actually it sets off a warning. Which is the right response from the > core mm code because specifying __GFP_NOFAIL and __GFP_NOWAIT makes no > sense.
Yes, this is what I meant. Kmemleak did a trick to fool fault-injection by passing in __GFP_NOFAIL, but it doesn't make sense for non-blockable allocation.
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