On Fri, 2016-04-15 at 20:56 +0200, Denys Vlasenko wrote: > On 04/15/2016 04:40 PM, James Bottomley wrote: > > On Fri, 2016-04-15 at 12:36 +0200, Denys Vlasenko wrote: > > > More info here: > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70646 > > > > This bug is under investigation, so I'd rather not alter code for a > > gcc > > bug until we know if we can supply options to fix it rather than > > changing code. > > > Background. The bug exists in gcc for 2 years, but it is rather > hard to trigger, so nobody noticed. We know this ... linux-scsi is on the cc for the other thread on this. > Unfortunately for kernel, these two commits landed in Linus tree > in March 16 and 17: > > > On 04/13/2016 05:36 AM, Josh Poimboeuf wrote: > > It occurs with the combination of the following two recent commits: > > > > - bc27fb68aaad ("include/uapi/linux/byteorder, swab: force inlining > > of some byteswap operations") > > - ef3fb2422ffe ("scsi: fc: use get/put_unaligned64 for wwn access") > > > and now *many* users of qla2x00 and new-ish gcc are going to > very much notice it, as their kernels will start crashing reliably. > > The commits can be reverted, sure, but they per se do not contain > anything unusual. They, together with not very typical construct > in qla2x00_get_host_fabric_name, one > which boils down to "swab64p(constant_array_of_8_bytes)", > just happen to nudge gcc in a right way to finally trigger the bug. > > So I came with another idea how to forestall the imminent deluge of > qla2x00 oops reports - this patch. There are actually a raft of checkers that run the upstream code which aren't seeing any problem; likely because the code is harder to trigger than you think. So, lets wait until the resolution of the other thread before we panic, especially since we're only at -rc3. James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
