On Tue, Jul 23, 2019 at 05:31:33PM +0200, Carlos Maiolino wrote: > CC'ing Jeff so he can maybe chime in too. > > > > Er, what problem does this solve? Does holding on to the pag spinlock > > too long while memory freeing causes everything else to stall? When is > > memory freeing slow enough to cause a noticeable impact? > > Jeff detected it when using this patch: > > https://marc.info/?l=linux-mm&m=156388753722881&w=2 > > At first I don't see any specific problem, but I don't think we are supposed to > use kmem_free() inside interrupt context anyway. So, even though there is no > visible side effect, it should be fixed IMHO. With the patch above, the side > effect is a bunch of warnings :P This is going to break lots of places in xfs. While we have separate allocation side wrappers for plain kmalloc vs using a vmalloc fallback we always use the same free side wrapper. We could fix this by adding a kmem_free_large and switch all places that allocated using kmem_alloc_large to that, but it will require a bit of work.
