On Tue, Mar 14, 2017 at 05:57:45PM +0100, Luis R. Rodriguez wrote: > On Tue, Mar 07, 2017 at 04:35:28PM -0800, Darrick J. Wong wrote: > > The sole remaining caller of kmem_zalloc_greedy is bulkstat, which uses > > it to grab 1-4 pages for staging of inobt records. The infinite loop in > > the greedy allocation function is causing hangs[1] in generic/269, so > > just get rid of the greedy allocator in favor of kmem_zalloc_large. > > This makes bulkstat somewhat more likely to ENOMEM if there's really no > > pages to spare, but eliminates a source of hangs. > > > > [1] http://lkml.kernel.org/r/20170301044634.rgidgdqqiiwsmfpj%40XZHOUW.usersys.redhat.com > > > > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > --- > > v2: remove single-page fallback > > --- > > Since this fixes a hang how about *at the very least* a respective Fixes tag ? > This fixes an existing hang so what are the stable considerations here ? I > realize the answer is not easy but figured its worth asking. I didn't think it was appropriate to "Fixes: 77e4635ae1917" since we're not fixing _greedy so much as we are killing it. The patch fixes an infinite retry hang when bulkstat tries a memory allocation that cannot be satisfied; and having done that, realizes there are no remaining callers of _greedy and garbage collects it. The code that was there before also seems capable of sleeping forever, I think. So the minimally invasive fix is to apply the allocation conversion in bulkstat, and if there aren't any other callers of _greedy then you can get rid of it too. > FWIW I trace kmem_zalloc_greedy()'s introduction back to 2006 77e4635ae1917 > ("[XFS] Add a greedy allocation interface, allocating within a min/max size > range.") through v2.6.19 days... --D > > Luis > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html
