> -----Original Message----- > From: Song Bao Hua (Barry Song) > Sent: Tuesday, December 22, 2020 3:03 PM > To: 'Vitaly Wool' <vitaly.w...@konsulko.com> > Cc: Shakeel Butt <shake...@google.com>; Minchan Kim <minc...@kernel.org>; Mike > Galbraith <efa...@gmx.de>; LKML <linux-kernel@vger.kernel.org>; linux-mm > <linux...@kvack.org>; Sebastian Andrzej Siewior <bige...@linutronix.de>; > NitinGupta <ngu...@vflare.org>; Sergey Senozhatsky > <sergey.senozhatsky.w...@gmail.com>; Andrew Morton > <a...@linux-foundation.org>; tiantao (H) <tiant...@hisilicon.com> > Subject: RE: [PATCH] zsmalloc: do not use bit_spin_lock > > > > I'm still not convinced. Will kmap what, src? At this point src might become > just a bogus pointer. > > As long as the memory is still there, we can kmap it by its page struct. But > if > it is not there anymore, we have no way. > > > Why couldn't the object have been moved somewhere else (due to the > > compaction > mechanism for instance) > > at the time DMA kicks in? > > So zs_map_object() will guarantee the src won't be moved by holding those > preemption-disabled lock? > If so, it seems we have to drop the MOVABLE gfp in zswap for zsmalloc case? >
Or we can do get_page() to avoid the movement of the page. > > > > > > > > ~Vitaly > > > > Thanks > Barry
