On Sun, May 24, 2015 at 09:34:04PM +0200, Christoffer Dall wrote: > Hi all, > > I noticed a regression on my arm64 APM X-Gene system a couple > of weeks back. I would occassionally see the system lock up and see RCU > stalls during the caching phase of kernbench. I then wrote a small > script that does nothing but cache the files > (http://paste.ubuntu.com/11324767/) and ran that in a loop. On a known > bad commit (v4.1-rc2), out of 25 boots, I never saw it get past 21 > iterations of the loop. I have since tried to run a bisect from v3.19 to > v4.0 using 100 iterations as my criteria for a good commit. > > This resulted in the following first bad commit: > > 10359213d05acf804558bda7cc9b8422a828d1cd > (mm: incorporate read-only pages into transparent huge pages, 2015-02-11) > > Indeed, running the workload on v4.1-rc4 still produced the behavior, > but reverting the above commit gets me through 100 iterations of the > loop. > > I have not tried to reproduce on an x86 system. Turning on a bunch > of kernel debugging features *seems* to hide the problem. My config for > the XGene system is defconfig + CONFIG_BRIDGE and > CONFIG_POWER_RESET_XGENE. > > Please let me know if I can help test patches or other things I can > do to help. I'm afraid that by simply reading the patch I didn't see > anything obviously wrong with it which would cause this behavior. I don't see the problem on x86. Some backtraces could help to track it down. -- Kirill A. Shutemov -- 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>