Christoph Hellwig <hch at infradead.org> writes: > On Thu, Jun 16, 2016 at 11:22:46AM +0200, Vitaly Kuznetsov wrote: >> _count -> _refcount rename in commit 0139aa7b7fa12 ("mm: rename _count, >> field of the struct page, to _refcount") broke kdump. makedumpfile(8) does >> stuff like READ_MEMBER_OFFSET("page._count", page._count) and fails. While >> it is definitely possible to fix this particular tool I'm not sure about >> other tools which might be doing the same. >> >> I suggest we remember the "we don't break userspace" rule and revert for >> 4.7 while it's not too late. > > Err, sorry - this is not "userspace". It's crazy crap digging into > kernel internal structure. > > The rename was absolutely useful, so fix up your stinking pike in kdump. Ok, sure, I'll send a patch to it. I was worried about other tools out there which e.g. inspect /proc/vmcore. As it is something we support some conservatism around it is justified. -- Vitaly