On Thu 14-07-16 19:07:52, Ondrej Kozina wrote: > On 07/14/2016 05:31 PM, Michal Hocko wrote: > > On Thu 14-07-16 16:08:28, Ondrej Kozina wrote: > > [...] > > > As Mikulas pointed out, this doesn't work. The system froze as well with the > > > patch above. Will try to tweak the patch with Mikulas's suggestion... > > > > Thank you for testing! Do you happen to have traces of the frozen > > processes? Does the flusher still gets throttled because the bias it > > gets is not sufficient. Or does it get throttled at a different place? > > > > Sure. Here it is (including sysrq+t and sysrq+w output): https://okozina.fedorapeople.org/bugs/swap_on_dmcrypt/4.7.0-rc7+/1/4.7.0-rc7+.log Thanks a lot! This is helpful. [ 162.716376] active_anon:107874 inactive_anon:108176 isolated_anon:64 [ 162.716376] active_file:1086 inactive_file:1103 isolated_file:0 [ 162.716376] unevictable:0 dirty:0 writeback:69824 unstable:0 [ 162.716376] slab_reclaimable:3119 slab_unreclaimable:24124 [ 162.716376] mapped:2165 shmem:57 pagetables:1509 bounce:0 [ 162.716376] free:701 free_pcp:0 free_cma:0 No surprise that PF_LESS_THROTTLE didn't help. It gives some bias but considering how many pages are under writeback it cannot possibly help to prevent from sleeping in throttle_vm_writeout. I suppose adding the following on top of the memalloc patch helps, right? It is an alternative to what you were suggesting in other email but it doesn't affect current_may_throttle paths which I would rather not touch. --- diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 7fbb2d008078..a37661f1a11b 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1971,6 +1971,9 @@ void throttle_vm_writeout(gfp_t gfp_mask) unsigned long background_thresh; unsigned long dirty_thresh; + if (current->flags & PF_LESS_THROTTLE) + return; + for ( ; ; ) { global_dirty_limits(&background_thresh, &dirty_thresh); dirty_thresh = hard_dirty_limit(&global_wb_domain, dirty_thresh); -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>