On Tue, Mar 8, 2022 at 9:04 PM Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > On Tue, Mar 8, 2022 at 11:27 AM Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > So I think the fix for this all might be something like the attached > > (TOTALLY UNTESTED)! > > Still entirely untested, but I wrote a commit message for it in the > hopes that this actually works and Andreas can verify that it fixes > the issue. > > Same exact patch, it's just now in my local experimental tree as a commit. Seems to be working on s390x for this test case at least; the kind of trace I'm getting is: swpd free buff cache read_fault read_fault_race read_lock_stolen min_flt maj_flt 0 2249156 6352 783924 0 0 0 1142 157566 0 2076308 5896 961680 0 0 0 1 52702 0 1938824 5896 1186184 0 0 0 506 56708 0 1719640 5896 1404268 0 0 0 0 54604 0 1454772 5896 1590780 0 0 0 741 45044 0 1213924 5896 1828048 0 0 0 0 60716 0 995300 5896 2046172 0 0 0 0 54408 0 843140 5896 2264756 0 0 0 622 54412 0 630328 5896 2478980 0 0 0 0 53578 0 446096 5896 2675508 0 0 0 569 48286 0 315156 5896 2806336 0 0 0 0 33396 0 169068 5896 2954052 0 0 0 0 36151 0 33980 5064 3095736 0 0 0 681 49776 0 136596 1068 3012612 0 0 0 0 48800 0 51128 1068 2887180 0 0 0 48605 49288 0 42276 1068 2895960 0 0 0 1 49776 0 45496 944 2890752 0 0 0 35 49288 0 38592 944 2896364 3 0 0 124 44817 0 37100 944 2976368 46 0 0 25412 27301 0 37204 928 2981564 0 0 0 0 62316 0 52384 928 2965820 0 0 0 0 30020 0 32296 928 2830228 0 0 0 61824 49281 0 36208 928 2831920 0 0 0 0 49599 0 37424 928 2830176 0 0 0 0 48800 0 35676 928 2830256 0 0 0 104 46282 0 140932 928 2987628 0 0 0 628 47871 0 32128 928 3095628 0 0 0 0 49086 0 40900 920 2752240 0 0 0 79824 131220 0 67380 920 2723188 0 0 0 39 61666 0 42560 884 2747124 0 0 0 4 27266 0 43296 880 3036340 16 0 0 6557 79270 0 160616 832 3043056 0 0 0 379 44515 0 36892 688 2864892 0 0 0 49524 59299 0 38004 688 2866088 0 0 0 0 57308 0 39732 568 2860468 0 0 0 49 51105 0 37364 568 2861224 0 0 0 0 0 0 35432 568 2863220 0 0 0 0 0 0 38996 568 2859308 0 0 0 0 0 0 40808 568 2857044 0 0 0 0 0 0 35360 568 2865076 1 0 0 4 0 0 31592 564 2861216 123 0 0 50577 29984 0 32816 564 2857012 0 0 0 0 130047 0 39588 564 2785968 0 0 0 66022 50499 0 37752 564 2788028 0 0 0 0 53397 0 35576 460 2789696 0 0 0 0 52803 0 35944 460 2790020 0 0 0 13 37240 0 38280 460 2787336 0 0 0 0 0 0 38588 460 2786444 0 0 0 0 0 0 36940 460 2785644 0 0 0 0 0 0 39560 460 2784648 0 0 0 0 0 0 115032 452 2777568 4 0 0 16 0 0 44772 452 2808116 0 0 0 71280 139232 0 35828 452 2812368 0 0 0 0 57886 0 33420 452 2815904 0 0 0 0 56762 0 222932 452 2901480 0 0 0 1761 51125 0 34988 452 3085360 0 0 0 0 55638 0 32716 336 3049448 0 0 0 6398 54202 0 38572 336 3050040 0 0 0 0 54172 0 250724 336 3052404 0 0 0 422 37779 0 39204 264 2754388 0 0 0 78287 55056 0 39564 264 2752932 0 0 0 0 52712 0 38108 232 2752660 0 0 0 38 53350 0 32448 196 2753920 0 0 0 2 29024 0 36536 196 2754172 0 0 0 0 0 0 36116 196 2749096 0 0 0 0 0 0 35968 196 2754416 0 0 0 0 0 0 33744 196 2756908 24 0 0 96 0 0 33428 196 2870904 16 0 0 48271 123984 0 124932 196 2916896 0 0 0 14925 47427 0 44764 196 2993408 0 0 0 0 57057 0 46396 196 2990544 0 0 0 0 49864 0 39224 196 2996332 0 0 0 0 3124 0 34524 196 2844232 0 0 0 49321 6308 0 34088 92 2794136 0 0 0 14846 62955 0 38680 92 2792752 0 0 0 0 48056 0 36756 92 2793916 0 0 0 36 48994 0 37336 92 2791996 0 0 0 4 18127 0 38844 92 2760304 26 0 0 61323 48345 0 42584 92 2755980 0 0 0 0 53772 0 39436 92 2758252 0 0 0 804 51220 0 33408 88 2764016 0 0 0 339 32307 0 38228 88 2759052 0 0 0 0 0 0 36816 88 2760776 0 0 0 0 0 0 38624 88 2759628 0 0 0 0 0 0 38912 88 2752788 234 0 0 936 0 0 35640 88 3070384 394 0 0 2193 108219 0 38816 88 2716016 0 0 0 83715 55072 0 37084 88 2716076 0 0 0 0 50703 0 49256 88 2703460 0 0 0 0 51268 0 38256 72 2714892 0 0 0 0 38361 0 43468 72 2709640 0 0 0 0 0 0 38448 72 2715140 0 0 0 0 0 0 40536 72 2713412 0 0 0 0 0 0 36060 72 2711732 4 0 0 16 0 0 35804 72 2697600 65 0 0 88429 76050 0 42100 72 2687776 0 0 0 0 78018 0 44532 72 2682776 0 0 0 37 47051 0 57652 72 2911680 0 0 0 27636 60021 0 38196 72 2930916 0 0 0 0 39256 0 304060 72 2926132 0 0 0 6 41287 0 42524 72 3067232 0 0 0 446 58607 0 36244 72 3071536 0 0 0 0 45878 0 41052 72 2815772 0 0 0 59290 53910 0 38264 72 2816620 0 0 0 0 20666 0 39772 72 2815696 0 0 0 0 23975 0 37016 72 2817520 0 0 0 0 46818 0 39172 72 2889840 0 0 0 41578 47448 0 36440 72 2890160 0 0 0 1 48756 0 35028 72 2888492 0 0 0 0 49428 0 54364 72 2975816 0 0 0 14981 48084 0 36580 72 2992292 0 0 0 0 37284 0 35852 72 2992000 0 0 0 0 48168 0 36280 72 2833252 9 0 0 53762 48677 0 38916 72 2827892 0 0 0 0 48467 0 36996 72 2829432 0 0 0 0 48347 0 42524 68 2822216 0 0 0 0 32250 0 37060 68 2827612 0 0 0 0 0 0 38080 68 2827556 0 0 0 0 0 0 41660 68 2822936 0 0 0 0 0 0 32384 68 2824372 0 0 0 0 0 0 37468 68 2754364 58 0 0 70218 117793 0 36568 68 2756192 0 0 0 56 53470 0 125052 68 2906412 0 0 0 8070 49300 0 38468 68 2990660 0 0 0 0 49776 0 41180 68 3012140 0 0 0 684 49776 0 38044 68 3012908 0 0 0 1 50752 0 38924 68 2774392 0 0 0 56420 44877 0 36824 68 2777720 0 0 0 0 800 0 39172 68 2775236 0 0 0 0 1568 0 39748 68 2774740 0 0 0 0 960 0 35768 68 2778264 0 0 0 0 1920 0 40568 68 2773900 0 0 0 0 1696 0 41616 68 2773096 0 0 0 0 3712 0 42688 68 2772320 0 0 0 0 5408 0 39736 68 2774648 0 0 0 0 5152 This shows bursts of successful fault-ins in gfs2_file_read_iter (read_fault). The pauses in between might be caused by the storage; I'm not sure. I'd still let the caller of fault_in_safe_writeable() decide how much memory to fault in; the tight cap in fault_in_safe_writeable() doesn't seem useful. Also, you want to put in an extra L here: > Signed-off-by: linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Thanks, Andreas
