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Date: Sun, 22 Mar 2015 17:35:49 -0600 From: David Ahern <david.ahern@...cle.com> To: David Miller <davem@...emloft.net>, torvalds@...ux-foundation.org CC: sparclinux@...r.kernel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, Bob Picco <bpicco@...oft.net> Subject: Re: 4.0.0-rc4: panic in free_block On 3/22/15 4:23 PM, David Miller wrote: >> I don't even know which version of memcpy ends up being used on M7. >> Some of them do things like use VIS. I can follow some regular sparc >> asm, there's no way I'm even *looking* at that. Is it really ok to use >> VIS registers in random contexts? > > Yes, using VIS how we do is alright, and in fact I did an audit of > this about 1 year ago. This is another one of those "if this is > wrong, so much stuff would break" > > The only thing funny some of these routines do is fetch 2 64-byte > blocks of data ahead in the inner loops, but that should be fine > right? > > On the M7 we'll use the Niagara-4 memcpy. > > Hmmm... I'll run this silly sparc kernel memmove through the glibc > testsuite and see if it barfs. > I don't know if you caught Bob's message; he has a hack to bypass memcpy and memmove in mm/slab.c use a for loop to move entries. With the hack he is not seeing the problem. This is the hack: +static void move_entries(void *dest, void *src, int nr) +{ + unsigned long *dp = dest; + unsigned long *sp = src; + + for (; nr; nr--, dp++, sp++) + *dp = *sp; +} + and then replace the mempy and memmove calls in transfer_objects, cache_flusharray and drain_array to use move_entries. I just put it on 4.0.0-rc4 and ditto -- problem goes away, so it clearly suggests the memcpy or memmove are the root cause. David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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