On Tue, Jan 27, 2015 at 11:32 AM, Takashi Iwai <tiwai(a)suse.de> wrote:
the commit [320b2b8de126: mm: keep a guard page below a grow-down
stack segment] seems resulting in a regression with libsigsegv.
This is a case giving us a dilemma. Of course, we can "fix"
libsigsegv to handle SIGBUS gracefully. OTOH, this can be seen as a
user-space regression we'd like to avoid usually.
Yeah, no, that's obviously a kernel regression and needs to be fixed,
even if no sane program should care about SIGSEGV vs SIGBUS. But "sane
program" is irrelevant for the regression rule - somebody noticed.
The only reason it returns SIGBUS is that we don't have an equivalent
VM_FAULT_SIGSEGV error return. Which is something of an oversight,
but adding it is a pain too, simply because the callers are mainly the
architecture page fault handlers, so the VM_FAULT_SIGSEGV handling has
to be added to all of them.
Very annoying. The patch would look something like the attached -
Does this fix things for you?