> -----Original Message----- > From: Michal Hocko <mho...@kernel.org> > Sent: Monday, 17 June 2019 5:47 PM > To: Alastair D'Silva <alast...@au1.ibm.com> > Cc: alast...@d-silva.org; Arun KS <aru...@codeaurora.org>; Mukesh Ojha > <mo...@codeaurora.org>; Logan Gunthorpe <log...@deltatee.com>; Wei > Yang <richard.weiy...@gmail.com>; Peter Zijlstra <pet...@infradead.org>; > Ingo Molnar <mi...@kernel.org>; linux...@kvack.org; Qian Cai > <c...@lca.pw>; Thomas Gleixner <t...@linutronix.de>; Andrew Morton > <a...@linux-foundation.org>; Mike Rapoport <r...@linux.vnet.ibm.com>; > Baoquan He <b...@redhat.com>; David Hildenbrand <da...@redhat.com>; > Josh Poimboeuf <jpoim...@redhat.com>; Pavel Tatashin > <pasha.tatas...@soleen.com>; Juergen Gross <jgr...@suse.com>; Oscar > Salvador <osalva...@suse.com>; Jiri Kosina <jkos...@suse.cz>; linux- > ker...@vger.kernel.org > Subject: Re: [PATCH 4/5] mm/hotplug: Avoid RCU stalls when removing large > amounts of memory > > On Mon 17-06-19 14:36:30, Alastair D'Silva wrote: > > From: Alastair D'Silva <alast...@d-silva.org> > > > > When removing sufficiently large amounts of memory, we trigger RCU > > stall detection. By periodically calling cond_resched(), we avoid > > bogus stall warnings. > > > > Signed-off-by: Alastair D'Silva <alast...@d-silva.org> > > --- > > mm/memory_hotplug.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index > > e096c987d261..382b3a0c9333 100644 > > --- a/mm/memory_hotplug.c > > +++ b/mm/memory_hotplug.c > > @@ -578,6 +578,9 @@ void __remove_pages(struct zone *zone, unsigned > long phys_start_pfn, > > __remove_section(zone, __pfn_to_section(pfn), > map_offset, > > altmap); > > map_offset = 0; > > + > > + if (!(i & 0x0FFF)) > > + cond_resched(); > > We already do have cond_resched before __remove_section. Why is an > additional needed?
I was getting stalls when removing ~1TB of memory. -- Alastair D'Silva mob: 0423 762 819 skype: alastair_dsilva msn: alast...@d-silva.org blog: http://alastair.d-silva.org Twitter: @EvilDeece
