Hi, On Tue, 15 Mar 2016 15:16:11 +0100 Richard Weinberger <richard@xxxxxx> wrote: > Hi! > > We're facing this issue from 2014 on UBIFS: > http://www.spinics.net/lists/linux-fsdevel/msg79941.html Just to let you know I was able to reproduce the exact same bug on a sama5d3 with UBIFS + CMA enabled (CMA allocation through the generic DRM/CMA code), so I think we can exclude a platform specific bug. > > So sum up: > UBIFS does not allow pages directly marked as dirty. It want's everyone to do it via UBIFS's > ->wirte_end() and ->page_mkwirte() functions. > This assumption *seems* to be violated by CMA which migrates pages. > UBIFS enforces this because it has to account free space on the flash, > in UBIFS speak "budget", for details please see fs/ubifs/file.c. > > As in the report from 2014 the page is writable but not dirty. > The kernel has this debug patch applied: > http://www.spinics.net/lists/linux-fsdevel/msg80471.html > But our kernel is based on v4.4 and does *not* use proprietary modules. > > [ 213.450000] page:debe03c0 count:3 mapcount:1 mapping:dce4b5fc index:0x2f > [ 213.460000] flags: 0x9(locked|uptodate) > [ 213.460000] page dumped because: try_to_unmap_one > [ 213.470000] pte_write: 1 > [ 213.480000] UBIFS assert failed in ubifs_set_page_dirty at 1451 (pid 436) > [ 213.490000] CPU: 0 PID: 436 Comm: drm-stress-test Not tainted 4.4.4-00176-geaa802524636-dirty #1008 > [ 213.490000] Hardware name: Allwinner sun4i/sun5i Families > [ 213.490000] [<c0015e70>] (unwind_backtrace) from [<c0012cdc>] (show_stack+0x10/0x14) > [ 213.490000] [<c0012cdc>] (show_stack) from [<c02ad834>] (dump_stack+0x8c/0xa0) > [ 213.490000] [<c02ad834>] (dump_stack) from [<c0236ee8>] (ubifs_set_page_dirty+0x44/0x50) > [ 213.490000] [<c0236ee8>] (ubifs_set_page_dirty) from [<c00fa0bc>] (try_to_unmap_one+0x10c/0x3a8) > [ 213.490000] [<c00fa0bc>] (try_to_unmap_one) from [<c00fadb4>] (rmap_walk+0xb4/0x290) > [ 213.490000] [<c00fadb4>] (rmap_walk) from [<c00fb1bc>] (try_to_unmap+0x64/0x80) > [ 213.490000] [<c00fb1bc>] (try_to_unmap) from [<c010dc28>] (migrate_pages+0x328/0x7a0) > [ 213.490000] [<c010dc28>] (migrate_pages) from [<c00d0cb0>] (alloc_contig_range+0x168/0x2f4) > [ 213.490000] [<c00d0cb0>] (alloc_contig_range) from [<c010ec00>] (cma_alloc+0x170/0x2c0) > [ 213.490000] [<c010ec00>] (cma_alloc) from [<c001a958>] (__alloc_from_contiguous+0x38/0xd8) > [ 213.490000] [<c001a958>] (__alloc_from_contiguous) from [<c001ad44>] (__dma_alloc+0x23c/0x274) > [ 213.490000] [<c001ad44>] (__dma_alloc) from [<c001ae08>] (arm_dma_alloc+0x54/0x5c) > [ 213.490000] [<c001ae08>] (arm_dma_alloc) from [<c035cecc>] (drm_gem_cma_create+0xb8/0xf0) > [ 213.490000] [<c035cecc>] (drm_gem_cma_create) from [<c035cf20>] (drm_gem_cma_create_with_handle+0x1c/0xe8) > [ 213.490000] [<c035cf20>] (drm_gem_cma_create_with_handle) from [<c035d088>] (drm_gem_cma_dumb_create+0x3c/0x48) > [ 213.490000] [<c035d088>] (drm_gem_cma_dumb_create) from [<c0341ed8>] (drm_ioctl+0x12c/0x444) > [ 213.490000] [<c0341ed8>] (drm_ioctl) from [<c0121adc>] (do_vfs_ioctl+0x3f4/0x614) > [ 213.490000] [<c0121adc>] (do_vfs_ioctl) from [<c0121d30>] (SyS_ioctl+0x34/0x5c) > [ 213.490000] [<c0121d30>] (SyS_ioctl) from [<c000f2c0>] (ret_fast_syscall+0x0/0x34) > > The full kernellog can be found here: > http://code.bulix.org/ysuo9x-93716?raw > > So, let me repeat Artem's question from 2014: > > Now the question is: is it UBIFS which has incorrect assumptions, or this is the > > Linux MM which is not doing the right thing? I do not know the answer, let's see > > if the MM list may give us a clue. > > Thanks, > //richard -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>