> -----Original Message----- > From: Song Bao Hua (Barry Song) > Sent: Tuesday, December 22, 2020 3:03 PM > To: 'Vitaly Wool' <[email protected]> > Cc: Shakeel Butt <[email protected]>; Minchan Kim <[email protected]>; Mike > Galbraith <[email protected]>; LKML <[email protected]>; linux-mm > <[email protected]>; Sebastian Andrzej Siewior <[email protected]>; > NitinGupta <[email protected]>; Sergey Senozhatsky > <[email protected]>; Andrew Morton > <[email protected]>; tiantao (H) <[email protected]> > 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
