On Thu, Feb 2, 2017 at 11:19 PM, Jacob Champion <[email protected]> wrote: > > Idle thoughts: "Cannot access memory" in this case could be a red herring, > if Niklas' gdb can't peer into mmap'd memory spaces [1]. It seems reasonable > that the data in question could be mmap'd, given the nice round address and > 4 MiB length (equal to APR_MMAP_LIMIT). > > That doesn't mean we're looking in the wrong place, though, since SIGBUS can > also be generated by an out-of-bounds access to an mmap'd region.
Right, looks like the memory has been unmapped though (SIGBUS) before being (re)used. Does "EnableMMAP off" help or produce another backtrace? > > Niklas, what version of APR are you using? Are you serving large (> 4 MiB) > static files? I have not been able to reproduce so far (Ubuntu 16.04, httpd > 2.4.25 + mod_ssl + mpm_event). The original file bucket comes from mod_cache, and indeed looks larger than 4MB. If it were (htcache)cleaned while being served, SIGBUS shouldn't happen still since we hold an fd (and reference) on it... Regards, Yann.
