From mboxrd@z Thu Jan 1 00:00:00 1970 From: mhocko@kernel.org (Michal Hocko) Date: Mon, 13 Nov 2017 15:11:40 +0100 Subject: linux-next: Tree for Nov 7 In-Reply-To: <20171113092006.cjw2njjukt6limvb@dhcp22.suse.cz> References: <20171107162217.382cd754@canb.auug.org.au> <20171108142050.7w3yliulxjeco3b7@dhcp22.suse.cz> <20171110123054.5pnefm3mczsfv7bz@dhcp22.suse.cz> <20171113092006.cjw2njjukt6limvb@dhcp22.suse.cz> Message-ID: <20171113141140.cns5fxt5jg4zdedb@dhcp22.suse.cz> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon 13-11-17 10:20:06, Michal Hocko wrote: > [Cc arm and ppc maintainers] > > Thanks a lot for testing! > > On Sun 12-11-17 11:38:02, Joel Stanley wrote: > > On Fri, Nov 10, 2017 at 11:00 PM, Michal Hocko wrote: > > > Hi Joel, > > > > > > On Wed 08-11-17 15:20:50, Michal Hocko wrote: > > > [...] > > >> > There are a lot of messages on the way up that look like this: > > >> > > > >> > [ 2.527460] Uhuuh, elf segement at 000d9000 requested but the > > >> > memory is mapped already > > >> > [ 2.540160] Uhuuh, elf segement at 000d9000 requested but the > > >> > memory is mapped already > > >> > [ 2.546153] Uhuuh, elf segement at 000d9000 requested but the > > >> > memory is mapped already > > >> > > > >> > And then trying to run userspace looks like this: > > >> > > >> Could you please run with debugging patch posted > > >> http://lkml.kernel.org/r/20171107102854.vylrtaodla63kc57 at dhcp22.suse.cz > > > > > > Did you have chance to test with this debugging patch, please? > > > > Lots of this: > > > > [ 1.177266] Uhuuh, elf segement at 000d9000 requested but the memory is mapped already, got 000dd000 > > [ 1.177555] Clashing vma [dd000, de000] flags:100873 name:(null) > > This smells like the problem I've expected that mmap with hint doesn't > respect the hint even though there is no clashing mapping. The above > basically says that we didn't map at 0xd9000 but it has placed it at > 0xdd000. The nearest (clashing) vma is at 0xdd000 so this is our new > mapping. find_vma returns the closest vma (with addr < vm_end) for the > given address 0xd9000 so this address cannot be mapped by any other vma. > > Now that I am looking at arm's arch_get_unmapped_area it does perform > aligning for shared vmas. Sorry for confusion here. These are not shared mappings as pointed out by Russell in a private email. I got confused by the above flags which I have misinterpreted as bit 0 set => MAP_SHARED. These are vm_flags obviously so the bit 0 is VM_READ. Sorry about the confusion. The real reason we are doing the alignment is that we do a file mapping /* * We only need to do colour alignment if either the I or D * caches alias. */ if (aliasing) do_align = filp || (flags & MAP_SHARED); I am not really familiar with this architecture to understand why do we need aliasing for file mappings, though. -- Michal Hocko SUSE Labs