Hi Matt, On Mon, Jan 22, 2018 at 5:36 PM, Matt Redfearn <matt.redfearn@xxxxxxxx> wrote: > > Hi Serge, > > > On 17/01/18 22:22, Serge Semin wrote: >> >> Even though it's common to see the architecture code using both >> bootmem and memblock early memory allocators, it's not good for >> multiple reasons. First of all, it's redundant to have two >> early memory allocator while one would be more than enough from >> functionality and stability points of view. Secondly, some new >> features introduced in the kernel utilize the methods of the most >> modern allocator ignoring the older one. It means the architecture >> code must keep the both subsystems up synchronized with information >> about memory regions and reservations, which leads to the code >> complexity increase, that obviously increases bugs probability. >> Finally it's better to keep all the architectures code unified for >> better readability and code simplification. All these reasons lead >> to one conclusion - arch code should use just one memory allocator, >> which is supposed to be memblock as the most modern and already >> utilized by the most of the kernel platforms. This patchset is >> mostly about it. >> >> One more reason why the MIPS arch code should finally move to >> memblock is a BUG somewhere in the initialization process, when >> CMA is activated: >> >> [ 0.248762] BUG: Bad page state in process swapper/0 pfn:01f93 >> [ 0.255415] page:8205b0ac count:0 mapcount:-127 mapping: (null) index:0x1 >> [ 0.263172] flags: 0x40000000() >> [ 0.266723] page dumped because: nonzero mapcount >> [ 0.272049] Modules linked in: >> [ 0.275511] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.88-module #5 >> [ 0.282900] Stack : 00000000 00000000 80b6dd6a 0000003a 00000000 00000000 80930000 8092bff4 >> 86073a14 80ac88c7 809f21ac 00000000 00000001 80b6998c 00000400 00000000 >> 80a00000 801822e8 80b6dd68 00000000 00000002 00000000 809f8024 86077ccc >> 80b80000 801e9328 809fcbc0 00000000 00000400 00010000 86077ccc 86073a14 >> 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 >> ... >> [ 0.323148] Call Trace: >> [ 0.325935] [<8010e7c4>] show_stack+0x8c/0xa8 >> [ 0.330859] [<80404814>] dump_stack+0xd4/0x110 >> [ 0.335879] [<801f0bc0>] bad_page+0xfc/0x14c >> [ 0.340710] [<801f0e04>] free_pages_prepare+0x1f4/0x330 >> [ 0.346632] [<801f36c4>] __free_pages_ok+0x2c/0x104 >> [ 0.352154] [<80b23a40>] init_cma_reserved_pageblock+0x5c/0x74 >> [ 0.358761] [<80b29390>] cma_init_reserved_areas+0x1b4/0x240 >> [ 0.365170] [<8010058c>] do_one_initcall+0xe8/0x27c >> [ 0.370697] [<80b14e60>] kernel_init_freeable+0x200/0x2c4 >> [ 0.376828] [<808faca4>] kernel_init+0x14/0x104 >> [ 0.381939] [<80107598>] ret_from_kernel_thread+0x14/0x1c >> >> The bugus pfn seems to be the one allocated for bootmem allocator >> pages and hasn't been freed before letting the CMA working with its >> areas. Anyway the bug is solved by this patchset. >> >> Another reason why this patchset is useful is that it fixes the fdt >> reserved-memory nodes functionality for MIPS. Really it's bug to have >> the fdt reserved nodes scanning before the memblock is >> fully initialized (calling early_init_fdt_scan_reserved_mem before >> bootmem_init is called). Additionally no-map flag of the >> reserved-memory node hasn't been taking into account. This patchset >> fixes all of these. >> >> As you probably remember I already did another attempt to merge a >> similar functionality into the kernel. This time the patchset got >> to be less complex (14 patches vs 21 last time) and fixes the >> platform code like SGI IP27 and Loongson3, which due to being >> NUMA introduce its own memory initialization process. Although >> I have much doubt in SGI IP27 code operability in the first place, >> since it got prom_meminit() method of early memory initialization, >> which hasn't been called at any other place in the kernel. It must >> have been left there unrenamed after arch/mips/mips-boards/generic >> code had been discarded. >> >> Here are the list of folks, who agreed to perform some tests of >> the patchset: >> Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx> - Octeon2 >> Matt Redfearn <matt.redfearn@xxxxxxxx> - Loongson3, etc > > > > I have applied and tested these patches on various platforms that we have available here, and the kernel appears to boot and get to userspace as normal on the following platforms: > > UTM8 (Cavium Octeon III) > Creator CI20 A bit off-topic, but could you please Acked one of Marcin's patch that I re-submitted: https://patchwork.linux-mips.org/patch/17986/ I believe CI20 wont boot from upstream kernel, since you are testing patch I am guessing you have a running system (unless of course you tweaked your u-boot env vars or use another different patch). Thanks for your help
