Am Donnerstag, den 03.09.2015, 17:28 +0900 schrieb Yongtaek Lee: > > On Thu, Sep 03, 2015 at 11:24:47AM +0900, Yongtaek Lee wrote: > > > default value of vmalloc_min was set 0xf0000000 for ARM by commit > > > 0536bdf3. But actually vmalloc_min is 0xef800000 not 0xf0000000. > > > > > > VMALLOC_END - (240 << 20) - VMALLOC_OFFSET) > > > 0xff000000 - 0x0f000000 - 0x00800000 = 0xef800000 > > > > > > In case of 768MB ram without CONFIG_HIGHMEM=y, last 8MB could not be > > > allocated. Kernel log also print out warning message as below. > > > "Truncating RAM at 80000000-afffffff to -af7fffff (vmalloc region > > > overlap)." > > > > > > Although it could be solved by state "vmalloc=size" in cmdline but i think > > > it would be better to change default value to 232 from 240. > > > > > > Signed-off-by: Yongtaek Lee <ytk....@samsung.com> > > > > I fail to see what the problem is here. You're adjusting the size of the > > vmalloc space to accomodate the size of RAM you have. That's not a bug. > > I will explain more about problem. > It could happened with 768MB RAM device and CONFIG_HIGHMEN is not set. > "vmalloc=size" also not stated so that default value of vmalloc_min will be > used to calculate lowmem end address.
> before applying patch. > [ 0.000000] [0: swapper: 0] [c0] Truncating RAM at > 80000000-afffffff to -af7fffff (vmalloc region overlap). > > [ 0.000000] [0: swapper: 0] [c0] Memory: 106MB 652MB = 758MB > total > [ 0.000000] [0: swapper: 0] [c0] Memory: 669892k/669892k > available, 108348k reserved, 0K highmem > [ 0.000000] [0: swapper: 0] [c0] Virtual kernel memory layout: > [ 0.000000] [0: swapper: 0] vector : 0xffff0000 - > 0xffff1000 ( 4 kB) > [ 0.000000] [0: swapper: 0] fixmap : 0xfff00000 - > 0xfffe0000 ( 896 kB) > [ 0.000000] [0: swapper: 0] vmalloc : 0xf0000000 - > 0xff000000 ( 240 MB) > [ 0.000000] [0: swapper: 0] lowmem : 0xc0000000 - > 0xef800000 ( 760 MB) > [ 0.000000] [0: swapper: 0] modules : 0xbf000000 - > 0xc0000000 ( 16 MB) > [ 0.000000] [0: swapper: 0] .text : 0xc0008000 - > 0xc09bbee0 (9936 kB) > [ 0.000000] [0: swapper: 0] .init : 0xc09bc000 - > 0xc0a2b740 ( 446 kB) > [ 0.000000] [0: swapper: 0] .data : 0xc0a2c000 - > 0xc0ac4088 ( 609 kB) > [ 0.000000] [0: swapper: 0] .bss : 0xc0ac4088 - > 0xc0d3e7b4 (2538 kB) > > after applying patch. > [ 0.000000] [0: swapper: 0] [c0] Memory: 106MB 660MB = 766MB > total > [ 0.000000] [0: swapper: 0] [c0] Memory: 678004k/678004k > available, 108428k reserved, 0K highmem > [ 0.000000] [0: swapper: 0] [c0] Virtual kernel memory layout: > [ 0.000000] [0: swapper: 0] vector : 0xffff0000 - > 0xffff1000 ( 4 kB) > [ 0.000000] [0: swapper: 0] fixmap : 0xfff00000 - > 0xfffe0000 ( 896 kB) > [ 0.000000] [0: swapper: 0] vmalloc : 0xf0800000 - > 0xff000000 ( 232 MB) > [ 0.000000] [0: swapper: 0] lowmem : 0xc0000000 - > 0xf0000000 ( 768 MB) > [ 0.000000] [0: swapper: 0] modules : 0xbf000000 - > 0xc0000000 ( 16 MB) > [ 0.000000] [0: swapper: 0] .text : 0xc0008000 - > 0xc09bbee0 (9936 kB) > [ 0.000000] [0: swapper: 0] .init : 0xc09bc000 - > 0xc0a2b740 ( 446 kB) > [ 0.000000] [0: swapper: 0] .data : 0xc0a2c000 - > 0xc0ac4088 ( 609 kB) > [ 0.000000] [0: swapper: 0] .bss : 0xc0ac4088 - > 0xc0d3e7b4 (2538 kB) > > As i know "vmalloc=size" is not mandatory so that i think default value of > vmalloc_min is wrong. > So, if we go and apply your logic to a 1GB system we should resize the vmalloc area to 0 bytes in order to avoid RAM truncation without CONFIG_HIGHMEM? Sorry, but the only sane options here are to either live with the truncation, enable CONFIG_HIGHMEM, or set vmalloc size manually. Changing a default value that affects everyone for the benefit of your specific use-case isn't a sane option. Regards, Lucas -- Pengutronix e.K. | Lucas Stach | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
