Eyes Above The Waves

Robert O'Callahan. Christian. Repatriate Kiwi. Hacker.

Friday 19 June 2015

Bug In Newer Linux Kernels Affecting rr

As of kernel 4.0.4 (and probably earlier), writing to /proc/.../mem at a page which is mapped PROT_NONE causes a kernel BUG at mm/memory.c, which kills the writing process. This breaks rr, although I have a workaround which I'm about to land; the workaround temporarily makes the PROT_NONE regions we're writing to PROT_WRITE.

Trevor reported this in the kernel bugzilla already, though I was able to come up with a nice small test program.