Messages in this thread | | | From | Pavel Tatashin <> | Date | Wed, 7 Mar 2018 13:01:32 -0500 | Subject | Re: [PATCH v2] mm: might_sleep warning |
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> Hi, > > I've noticed that this function first disables the on-demand > initialization, and then runs the kthreads. Doesn't that leave a window > where allocations can fail? The chances are probably small, but I think > it would be better to avoid it completely, rare failures suck. > > Fixing that probably means rethinking the whole synchronization more > dramatically though :/ > > Vlastimil
Hi Vlastimil,
You are right, there is a window, it is short, and probably not possible to reproduce, as it happens before user threads are started, and after init calls done by smp_init() are finished. The only way it can happen, as far as I can see, is if some device fires an interrupt, and interrupt handler decides to allocate a large chunk of memory. The small allocations will succeed, as zone grow function growth more than strictly requested, and also there are zones without deferred pages.
I will, however, think some more how to solve this problem to be future proof.
Thank you, Pavel
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