On Wed 03-02-16 14:58:06, David Rientjes wrote: > On Wed, 3 Feb 2016, Michal Hocko wrote: > > > Hi, > > this thread went mostly quite. Are all the main concerns clarified? > > Are there any new concerns? Are there any objections to targeting > > this for the next merge window? > > Did we ever figure out what was causing the oom killer to be called much > earlier in Tetsuo's http://marc.info/?l=linux-kernel&m=145096089726481 and >From the OOM report: [ 3902.430630] kthreadd invoked oom-killer: order=2, oom_score_adj=0, gfp_mask=0x27000c0(GFP_KERNEL|GFP_NOTRACK|0x100000) [ 3902.507561] Node 0 DMA32: 3788*4kB (UME) 184*8kB (UME) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 16624kB [ 5262.901161] smbd invoked oom-killer: order=2, oom_score_adj=0, gfp_mask=0x27000c0(GFP_KERNEL|GFP_NOTRACK|0x100000) [ 5262.983496] Node 0 DMA32: 1987*4kB (UME) 14*8kB (ME) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 8060kB [ 5269.764580] kthreadd invoked oom-killer: order=2, oom_score_adj=0, gfp_mask=0x27000c0(GFP_KERNEL|GFP_NOTRACK|0x100000) [ 5269.858330] Node 0 DMA32: 10648*4kB (UME) 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 42592kB > http://marc.info/?l=linux-kernel&m=145130454913757 ? [ 277.884512] Node 0 DMA32: 3438*4kB (UME) 791*8kB (UME) 3*16kB (UM) 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 20128kB [ 291.349097] Node 0 DMA32: 4221*4kB (UME) 1971*8kB (UME) 436*16kB (UME) 141*32kB (UME) 8*64kB (UM) 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 44652kB [ 302.916334] Node 0 DMA32: 4304*4kB (UM) 1181*8kB (UME) 59*16kB (UME) 7*32kB (ME) 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 27832kB [ 311.034251] Node 0 DMA32: 6*4kB (U) 2401*8kB (ME) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 19232kB [ 314.314336] Node 0 DMA32: 1180*4kB (UM) 1449*8kB (UME) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 16312kB [ 322.796256] Node 0 DMA32: 86*4kB (UME) 2474*8kB (UME) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 20136kB [ 330.826190] Node 0 DMA32: 1637*4kB (UM) 1354*8kB (UME) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 17380kB [ 332.846805] Node 0 DMA32: 4108*4kB (UME) 897*8kB (ME) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 23608kB [ 341.073722] Node 0 DMA32: 3309*4kB (UM) 1124*8kB (UM) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 22228kB [ 360.093794] Node 0 DMA32: 2719*4kB (UM) 97*8kB (UM) 14*16kB (UM) 37*32kB (UME) 27*64kB (UME) 3*128kB (UM) 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 15172kB [ 368.871173] Node 0 DMA32: 5042*4kB (UM) 248*8kB (UM) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 22152kB [ 379.279344] Node 0 DMA32: 2994*4kB (ME) 503*8kB (UM) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 16000kB [ 387.385740] Node 0 DMA32: 3638*4kB (UM) 115*8kB (UM) 1*16kB (U) 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 15488kB [ 391.228084] Node 0 DMA32: 3374*4kB (UME) 221*8kB (M) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 15264kB [ 395.683137] Node 0 DMA32: 3794*4kB (ME) 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 15176kB [ 399.890082] Node 0 DMA32: 4155*4kB (UME) 200*8kB (ME) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 18220kB [ 408.465169] Node 0 DMA32: 2804*4kB (ME) 203*8kB (UME) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 12840kB [ 416.447247] Node 0 DMA32: 5158*4kB (UME) 68*8kB (M) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 21176kB [ 418.799643] Node 0 DMA32: 3093*4kB (UME) 1043*8kB (UME) 2*16kB (M) 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 20748kB [ 428.109005] Node 0 DMA32: 2943*4kB (UME) 458*8kB (UME) 20*16kB (UME) 11*32kB (UME) 11*64kB (ME) 4*128kB (UME) 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 17324kB [ 439.032446] Node 0 DMA32: 2761*4kB (UM) 28*8kB (UM) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 11268kB [ 441.731018] Node 0 DMA32: 3130*4kB (UM) 338*8kB (UM) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 15224kB [ 442.070867] Node 0 DMA32: 590*4kB (ME) 827*8kB (ME) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 8976kB [ 442.245208] Node 0 DMA32: 1902*4kB (UME) 410*8kB (UME) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 10888kB There are cases where order-2 has some pages but I have commented on that here [1] > I'd like to take a look at the patch(es) that fixed it. I am not sure we can fix these pathological loads where we hit the higher order depletion and there is a chance that one of the thousands tasks terminates in an unpredictable way which happens to race with the OOM killer. As I've pointed out in [1] once the watermark check for the higher order allocation fails for the given order then we cannot rely on the reclaimable pages ever construct the required order. The current zone_reclaimable approach just happens to work for this particular load because the NR_PAGES_SCANNED gets reseted too often with a side effect of an undeterministic behavior. [1] http://lkml.kernel.org/r/20160120131355.GE14187@xxxxxxxxxxxxxx -- 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>