On Sun, 4 Aug 2019 09:23:17 +0000 "Artem S. Tashkinov" <aros@xxxxxxx> wrote: > Hello, > > There's this bug which has been bugging many people for many years > already and which is reproducible in less than a few minutes under the > latest and greatest kernel, 5.2.6. All the kernel parameters are set to > defaults. Thanks for report! > > Steps to reproduce: > > 1) Boot with mem=4G > 2) Disable swap to make everything faster (sudo swapoff -a) > 3) Launch a web browser, e.g. Chrome/Chromium or/and Firefox > 4) Start opening tabs in either of them and watch your free RAM decrease We saw another corner-case cpu hog report under memory pressure also with swap disabled. In that report the xfs filesystem was an factor with CONFIG_MEMCG enabled. Anything special, say like kernel:watchdog: BUG: soft lockup - CPU#7 stuck for 22s! [leaker1:7193] or [ 3225.313209] Xorg: page allocation failure: order:4, mode:0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), nodemask=(null),cpuset=/,mems_allowed=0 in your kernel log? > > Once you hit a situation when opening a new tab requires more RAM than > is currently available, the system will stall hard. You will barely be > able to move the mouse pointer. Your disk LED will be flashing > incessantly (I'm not entirely sure why). You will not be able to run new > applications or close currently running ones. A cpu hog may come on top of memory hog in some scenario. > > This little crisis may continue for minutes or even longer. I think > that's not how the system should behave in this situation. I believe > something must be done about that to avoid this stall. Yes, Sir. > > I'm almost sure some sysctl parameters could be changed to avoid this > situation but something tells me this could be done for everyone and > made default because some non tech-savvy users will just give up on > Linux if they ever get in a situation like this and they won't be keen > or even be able to Google for solutions. I am not willing to repeat that it is hard to produce a pill for all patients, but the info you post will help solve the crisis sooner. Hillf
