On 08/31/2018, 02:10 PM, Pasha Tatashin wrote: > Thanks Jiri, I am now able to reproduce it with your new config. > > I have tried yesterday to enable sparsemem and deferred_struct_init on > x86_32, and that kernel booted fine, there must be something else in > your config that helps to trigger this problem. I am studying it now. > > [ 0.051245] Initializing CPU#0 > [ 0.051682] Initializing HighMem for node 0 (000367fe:0007ffe0) > [ 0.067499] BUG: unable to handle kernel NULL pointer dereference at > 00000028 > [ 0.068452] *pdpt = 0000000000000000 *pde = f000ff53f000ff53 > [ 0.069105] Oops: 0000 [#1] PREEMPT SMP PTI > [ 0.069595] CPU: 0 PID: 0 Comm: swapper Not tainted > 4.19.0-rc1-pae_pt_jiri #1 > [ 0.070382] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > BIOS 1.11.0-20171110_100015-anatol 04/01/2014 > [ 0.071545] EIP: free_unref_page_prepare.part.70+0x2c/0x50 > [ 0.072178] Code: 19 e9 ff 89 d1 55 c1 ea 11 c1 e9 07 8b 14 d5 44 52 > fd d6 81 e1 fc 03 00 00 89 e5 56 53 89 cb be 1d 00 00 00 c1 eb 05 83 e1 > 1f <8b> 14 9a 29 ce 89 f1 d3 ea 83 e2 07 89 50 10 b8 01 00 00 00 5b 5e > [ 0.074296] EAX: f4cfa000 EBX: 0000000a ECX: 00000010 EDX: 00000000 > [ 0.075005] ESI: 0000001d EDI: 0007ffe0 EBP: d6d41ed0 ESP: d6d41ec8 > [ 0.075714] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00210002 > [ 0.076508] CR0: 80050033 CR2: 00000028 CR3: 16f20000 CR4: 000406b0 > [ 0.077242] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 > [ 0.077934] DR6: fffe0ff0 DR7: 00000400 > [ 0.078380] Call Trace: > [ 0.078670] free_unref_page+0x3a/0x90 > [ 0.079136] __free_pages+0x25/0x30 > [ 0.079533] free_highmem_page+0x1e/0x50 > [ 0.079978] add_highpages_with_active_regions+0xd1/0x11f > [ 0.080592] set_highmem_pages_init+0x67/0x7d > [ 0.081076] mem_init+0x30/0x1fc page_to_pfn(pfn_to_page(pfn)) != pfn with my .config on pfns >= 0x60000: [ 0.157667] add_highpages_with_active_regions: pfn=5fffb pg=f55f9f4c pfn(pg(pfn)=5fffb sec=2 [ 0.159231] add_highpages_with_active_regions: pfn=5fffc pg=f55f9f70 pfn(pg(pfn)=5fffc sec=2 [ 0.161020] add_highpages_with_active_regions: pfn=5fffd pg=f55f9f94 pfn(pg(pfn)=5fffd sec=2 [ 0.163149] add_highpages_with_active_regions: pfn=5fffe pg=f55f9fb8 pfn(pg(pfn)=5fffe sec=2 [ 0.165204] add_highpages_with_active_regions: pfn=5ffff pg=f55f9fdc pfn(pg(pfn)=5ffff sec=2 [ 0.167216] add_highpages_with_active_regions: pfn=60000 pg=f4cfa000 pfn(pg(pfn)=c716a800 sec=3 So add_highpages_with_active_regions passes down page to free_highmem_page and later, free_unref_page does page_to_pfn(page) and __get_pfnblock_flags_mask operates on this modified pfn leading to crash – __pfn_to_section(pfn)->pageblock_flags is NULL! Note that __pfn_to_section(pfn)->pageblock_flags on the original pfn returns a valid bitmap. thanks, -- js suse labs
