David Miller wrote: [Mon Mar 23 2015, 12:25:30PM EDT] > From: David Miller <davem@xxxxxxxxxxxxx> > Date: Sun, 22 Mar 2015 22:19:06 -0400 (EDT) > > > I'll work on a fix. > > Ok, here is what I committed. David et al., let me know if you still > see the crashes with this applied. > > Of course, I'll queue this up for -stable as well. > > Thanks! > > ==================== > [PATCH] sparc64: Fix several bugs in memmove(). > > Firstly, handle zero length calls properly. Believe it or not there > are a few of these happening during early boot. > > Next, we can't just drop to a memcpy() call in the forward copy case > where dst <= src. The reason is that the cache initializing stores > used in the Niagara memcpy() implementations can end up clearing out > cache lines before we've sourced their original contents completely. > > For example, considering NG4memcpy, the main unrolled loop begins like > this: > > load src + 0x00 > load src + 0x08 > load src + 0x10 > load src + 0x18 > load src + 0x20 > store dst + 0x00 > > Assume dst is 64 byte aligned and let's say that dst is src - 8 for > this memcpy() call. That store at the end there is the one to the > first line in the cache line, thus clearing the whole line, which thus > clobbers "src + 0x28" before it even gets loaded. > > To avoid this, just fall through to a simple copy only mildly > optimized for the case where src and dst are 8 byte aligned and the > length is a multiple of 8 as well. We could get fancy and call > GENmemcpy() but this is good enough for how this thing is actually > used. > > Reported-by: David Ahern <david.ahern@xxxxxxxxxx> > Reported-by: Bob Picco <bpicco@xxxxxxxxxx> > Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> > --- Seems solid with 2.6.39 on M7-4. Jalap?no is happy with current sparc.git. -- 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>