Greetings mm wizards, Yesterday, while running master-rc7, I started updating one of my VM images from openSUSE Leap 42.3 -> Leap 15, figuring that could chug along while I do some work. That turned out to be a bad idea, box thrashed so badly it became unusable, which seems worthy of mention. Box is a garden variety i4790 box with 16G ram, half of which was donated to the VM. The VM image is 64GB, it's an OS plus all critical data mirror of my box (that fits on a USB stick). All was well until qemu RSS grew to the full 8G, at which time mm land went mad, swapping and thrashing horribly while 7G of ram remained free, see vmstat snippet below. It's NOT fully repeatable. I repeated the update using a 4.14 kernel, which behaved fine. Switching to 4.16, box thrashed, but not as badly as master had, nor did it keep as much ram free while doing so (~3G). Going back to master, mm land remained calm, I could use the box to do merges and whatnot (albeit being careful to take it easy on spinning rust) just fine while the VM did it's thing. Phase-of-moon behavior. This master vmstat snippet is with only the VM and a mostly idle GUI, as trying to do anything resembling work was a waste of time. procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 1 1 1740288 6896088 6828 128340 21 29 350 367 122 103 7 2 83 8 0 0 2 1740032 6902320 6828 128636 80 0 1392 18332 2429 8460 8 1 84 7 0 1 0 1740032 6898392 6828 128628 28 0 748 1640 2714 5838 6 2 87 6 0 1 0 1739776 6897864 6828 128668 164 0 1920 76 2558 7639 3 1 90 6 0 1 0 1739776 6895372 6828 129156 116 0 1896 60 2104 6456 3 1 91 5 0 0 0 1739776 6895116 6836 129192 196 0 700 168 2945 6677 7 1 89 4 0 0 1 1739776 6901092 6844 129292 40 0 1280 1572 3687 9739 5 3 86 6 0 1 0 1739776 6898884 6844 128236 12 64 276 1872 4596 18786 8 3 86 3 0 0 2 1747200 6910216 6760 127608 8 7380 288 7748 6725 38107 9 4 84 3 0 0 0 1756932 6918516 6724 126016 4 10064 172 10420 4711 10038 6 2 88 3 0 0 0 1773824 6936980 5728 125060 16 16836 420 17476 8741 9351 7 3 87 3 0 3 0 1782060 6943292 5692 128860 152 8252 2116 8536 4025 7673 5 2 88 6 0 1 0 1787452 6952868 5676 124644 56 5940 832 7672 3643 8052 6 2 88 5 0 0 0 1796428 6964452 5552 122140 0 8956 252 9124 5157 10080 5 3 91 1 0 0 1 1798476 6965416 5540 122844 20 1996 436 4436 3824 8384 5 3 91 1 0 2 0 1798476 6960840 5548 122828 16 0 212 4508 3559 9714 6 3 88 3 0 1 0 1798476 6960744 5556 122844 0 0 0 2408 4049 9925 7 3 89 1 0 0 0 1798476 6964672 5556 122932 0 0 164 620 4447 10341 4 4 91 1 0 0 1 1818228 6981740 5244 125548 8 19624 200 24472 10605 10163 6 4 86 5 0 1 1 1826304 6990164 4716 123008 4 8132 2156 10976 8670 14551 3 3 86 8 0 0 0 1829252 6992928 4544 121448 0 2992 1536 5508 4952 14444 3 4 86 7 0 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 3 0 1829252 6999360 4544 121448 0 0 0 0 3997 9792 3 4 92 0 0 0 0 1829252 6999092 4552 121568 0 0 192 172 3806 9246 4 4 91 0 0 1 0 1829252 6996960 4552 121576 0 0 0 0 4103 9302 4 4 92 0 0 2 0 1829252 6998984 4556 116736 0 40 4 212 4696 10466 3 5 91 1 0 1 0 1829252 6998404 4564 116904 184 0 312 36 4130 10487 3 3 93 1 0 0 0 1828228 7003720 4564 116992 1344 0 2736 6312 5595 17908 3 3 86 8 0 1 0 1828228 6998980 4572 117596 0 0 184 28 4347 10927 4 4 92 1 0 0 1 1827716 7000768 4572 117612 892 0 1484 18276 3538 9155 4 2 86 9 0 0 1 1826692 6992004 4572 119228 2404 0 3404 13100 3532 10196 7 1 80 12 0 1 0 1825156 6996056 4572 119540 1804 0 1876 15272 4086 13877 6 2 79 13 0 1 1 1823364 6994116 4580 119752 1812 0 2004 1840 3567 9753 6 2 79 14 0 0 2 1821828 6990780 4588 119816 1248 0 1648 48244 2728 7815 4 1 87 8 0 0 1 1818500 6984708 4588 120392 4020 0 4252 0 3833 9440 5 1 84 10 0 1 1 1816708 6987868 4588 120972 2604 0 2760 44032 2909 7877 5 1 86 8 0 0 1 1813892 6980520 4588 121300 2884 0 2948 38200 2803 7501 4 1 86 9 0 0 1 1811588 6982916 4596 121320 2132 0 2332 22492 2572 7048 8 1 84 6 0 0 3 1809284 6976112 4596 121480 2556 0 3004 16036 2820 7733 6 1 82 12 0 0 1 1806980 6968892 4596 122200 2904 0 3068 18384 4003 12307 4 2 81 13 0 0 1 1805188 6973156 4604 122428 2068 0 20068 12 2587 5901 1 1 87 11 0 1 2 1802116 6964912 4604 123264 4144 0 15640 72 3851 8710 2 1 82 14 0 1 0 1801092 6961472 4612 123680 1056 0 1720 328 3279 6709 6 1 86 6 0 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 1 0 1801092 6964964 4612 124068 0 0 712 1100 3987 9326 6 3 89 2 0 0 1 1801092 6962704 4612 124152 100 0 2116 1684 3718 10004 3 2 91 4 0 0 1 1801092 6961856 4612 124776 684 0 2576 5868 2439 6601 5 1 87 7 0 2 0 1801092 6963972 4620 125092 16 0 728 1816 2385 7271 2 2 88 8 0 0 0 1801092 6961656 4620 125048 0 0 0 0 3932 10045 4 3 93 0 0 2 0 1801092 6963992 4628 125048 0 0 384 6220 4780 12670 4 4 90 2 0 0 0 1801092 6963608 4628 125052 0 0 48 0 4342 10433 4 4 92 0 0 0 0 1801092 6963588 4628 125164 0 0 64 0 4347 11279 4 4 92 0 0 0 1 1800836 6961732 4636 125168 160 0 724 9632 3832 9534 4 4 89 3 0 1 0 1800324 6959144 4636 125356 480 0 2928 492 2661 6953 3 1 89 7 0 0 2 1796996 6957780 4644 125436 3496 0 4140 19848 2998 9266 6 2 84 8 0 0 1 1796228 6962888 4644 125484 668 0 1180 5020 3280 10379 6 2 81 12 0 0 1 1795972 6958552 4644 125668 444 0 1208 13716 3183 12078 2 2 88 8 0 1 1 1794948 6955404 4656 125808 1180 0 1312 5004 2966 11573 3 2 83 12 0 1 0 1794692 6958740 4656 126056 508 0 1324 4576 2738 6384 5 1 88 7 0 1 0 1794436 6953764 4664 126676 780 0 1952 1136 2625 5898 8 1 84 7 0 1 0 1794436 6955744 4664 126968 32 0 892 1320 3097 7727 7 2 88 4 0 0 0 1794436 6957320 4664 126968 4 0 4 16 3637 8272 5 3 92 0 0 2 0 1794436 6957408 4664 126972 0 0 84 0 3850 9745 4 4 92 0 0 1 0 1794436 6951244 4672 127064 8 0 80 4640 3333 9319 9 3 87 2 0 0 1 1794436 6956876 4672 127068 28 0 1452 1468 3919 9485 6 2 87 5 0
