Hi Sagar, On Thu, Sep 08, 2016 at 08:33:57PM -0700, Sagar Borikar wrote: > Hello, > > I am upgrading kernel for a MIPS Interaptive CPU from 3.10.60 to > 3.14.10 (stable) from: > https://www.linux-mips.org/wiki/Malta_Linux_Repository Unfortunately that wiki page needs updating. If you're upgrading anyway, I think we'd recommend switching all the way to a recent mainline kernel release / stable branch, e.g. 4.4 (LTS) or 4.7 (and maybe update to 4.9 (LTS) when it is released or when 4.7 goes EOL). I think all the stuff you'll need for interAptiv should be in mainline now anyway. > > The platform has non-contiguous low memory and high memory. After the > upgrade, highmem is not getting enabled due to max_low_pfn and > highend_pfn not being the same. > > The commit cce335ae47e231398269fb05fa48e0e9cbf289e0 introduced the > change apparently for sibyte platform. That change doesn't hold good > for all platforms where the high memory and low memory is sparsed. > > If I comment out only following change in arch/mips/mm/init.c, highmem > gets initialized properly. > > 296 if (cpu_has_dc_aliases && max_low_pfn != highend_pfn) { > 297 printk(KERN_WARNING "This processor doesn't support highmem." > 298 " %ldk highmem ignored\n", > 299 (highend_pfn - max_low_pfn) << (PAGE_SHIFT - 10)); > 300 max_zone_pfns[ZONE_HIGHMEM] = max_low_pfn; > 301 lastpfn = max_low_pfn; > 302 } I don't think we ever supported DCache aliasing + highmem in combination. If you want to use that memory your options are probably: - increase the page size to avoid dcache aliasing. - OR use EVA to increase the size of lowmem, which at the moment is a bit more involved. How much RAM do you have, and what does your physical memory map look like? Cheers James > > So wanted to know whether there is additional change required in > platform to work with above codebase. > Secondly, when the system proceeds (with commented code above), it > seems execve causes panic in copy_strings: > > Kernel bug detected[#1]: > CPU: 0 PID: 177 Comm: mcp Not tainted 3.14.10 #19 > task: 82c99070 ti: 829b0000 task.ti: 829b0000 > $ 0 : 00000000 81a40018 00000001 00000528 > $ 4 : 806805b0 00000294 00000000 81c76000 > $ 8 : 82c99070 fe001ffc 00000000 805d0000 > $12 : 00000000 00000000 00000000 00000001 > $16 : 8214a760 00000000 81a40010 82c2c580 > $20 : ffffffff 7fff7000 00000000 00000008 > $24 : 00000000 801182a0 > $28 : 829b0000 829b1e78 8214a760 801bb0bc > Hi : 000000e1 > Lo : 00077c44 > epc : 801bb014 copy_strings+0x304/0x394 > Not tainted > ra : 801bb0bc copy_strings_kernel+0x18/0x2c > Status: 1100fc03 KERNEL EXL IE > Cause : 10800034 > PrId : 0001a020 (MIPS interAptiv) > Modules linked in: > Process mcp (pid: 177, threadinfo=829b0000, task=82c99070, tls=770b82f0) > Stack : 00000080 00000000 00000000 00000000 00000017 829b1e98 00000000 00000000 > 8214a760 82bba0b0 fe001000 00000ff4 80000000 00000080 > 82bba0b0 81a40000 > 80b12b00 00000001 80b12b00 7fe5e66c 81c40000 801bb0bc > 80b12b00 82c2c630 > 82c2c580 00000080 82c2c580 801bc4d4 00000003 8013452c > 7649e000 7648fa08 > 82c99234 00000000 00000601 80b12b34 7649e000 7648fa08 > 7649e000 7fe5dc50 > ... > Call Trace: > [<801bb014>] copy_strings+0x304/0x394 > [<801bb0bc>] copy_strings_kernel+0x18/0x2c > [<801bc4d4>] do_execve+0x2fc/0x4c4 > [<8010d37c>] handle_sys+0x11c/0x140 > Code: 0806ec05 00000000 24020001 <00020336> 0c045e64 02002021 > 0c0651dd 02002021 0806ec1d > ---[ end trace ed487c3c490d886b ]--- > BUG: Bad rss-counter state mm:828bd6a0 idx:1 val:2 > > This panic occurs only when I spawn nested fork/execve. If I spawn the > process directly without nesting, I don't see this panic. > > Looks like there are several reports about "Bad rss-counter state" > panic with 3.14-stable. But I couldn't find any concrete solution to > the panic. > > Any pointers? > > Thanks > > Sagar >
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