On Mon, Jun 06, 2022 at 12:59:39PM -0700, Andrew Morton wrote: > On Mon, 6 Jun 2022 12:46:38 -0700 Minchan Kim <minchan@xxxxxxxxxx> wrote: > > > On Fri, Jun 03, 2022 at 02:57:47PM +0900, Jaewon Kim wrote: > > > The atomic page allocation failure sometimes happened, and most of them > > > seem to occur during boot time. > > > > > > <4>[ 59.707645] system_server: page allocation failure: order:0, mode:0xa20(GFP_ATOMIC), nodemask=(null),cpuset=foreground-boost,mems_allowed=0 > > > > ... > > > > > > > > The kswapd or other reclaim contexts may not prepare enough free pages > > > for too many atomic allocations occurred in short time. But zram may not > > > be helpful for this atomic allocation even though zram is used to > > > reclaim. > > > > > > To get one zs object for a specific size, zram may allocate serveral > > > pages. And this can be happened on different class sizes at the same > > > time. It means zram may consume more pages to reclaim only one page. > > > This inefficiency may consume all free pages below watmerk min by a > > > process having PF_MEMALLOC like kswapd. > > > > However, that's how zram has worked for a long time(allocate memory > > under memory pressure) and many folks already have raised min_free_kbytes > > when they use zram as swap. If we don't allow the allocation, swap out > > fails easier than old, which would break existing tunes. > > So is there a better way of preventing this warning? Just suppress it > with __GFP_NOWARN? For me, I usually tries to remove GFP_ATOMIC alllocation since the atomic allocation can be failed easily(zram is not only source for it). Otherwise, increase min_free_kbytes?
