[Let's CC some more people] On Wed 14-08-13 18:36:53, Ben Tebulin wrote: > Hello Michal, Johannes, Balbir, Kamezawa and Mailing lists! Hi, > Since v3.7.2 on two independent machines a very specific Git repository > fails in 9/10 cases on git-fsck due to an SHA1/memory failures. This > only occurs on a very specific repository and can be reproduced stably > on two independent laptops. Git mailing list ran out of ideas and for me > this looks like some very exotic kernel issue. > > After a _very long session of rebooting and bisecting_ the Linux kernel > (fortunately I had a SSD and ccache!) I was able to pinpoint the cause > to the following patch: > > *"mm: limit mmu_gather batching to fix soft lockups on !CONFIG_PREEMPT"* > 787f7301074ccd07a3e82236ca41eefd245f4e07 linux stable [1] > 53a59fc67f97374758e63a9c785891ec62324c81 upstream commit [2] Thanks for bisecting this up! I will look into this but I find it really strange. The patch only limits the number of batched pages to be freed. This might happen even without the patch, albeit less likely, when a new batch cannot be allocated. That being said, I do not see anything obviously wrong with the patch itself. Maybe we are not flushing those pages properly in some corner case which doesn't trigger normally. I will have to look at it but I really think this just exhibits a subtle bug in batch pages freeing. I have no objection to revert the patch for now until we find out what is really going on. > More details are available in my previous discussion on the Git mailing: > > http://thread.gmane.org/gmane.comp.version-control.git/231872 > > Never had any hardware/stability issues _at all_ with these machines. > Only one repo out of 112 is affected. It's a git-svn clone and even > recreated copies out of svn do trigger the same failure. > > I was able to bisect this error to this very specific commit. > Furthermore: Reverting this commit in 3.9.11 still solves the error. > > I assume this is a regression of the Linux kernel (not Git) and would > kindly ask you to revert the afore mentioned commits. > > Thanks! > - Ben > > > I'm not subscribed - please CC me. > > [1] https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=787f7301074ccd07a3e82236ca41eefd245f4e07 > [2] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=53a59fc67f97374758e63a9c785891ec62324c81 > -- 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>