On Mon, 31 Oct 2022, Pulavarty, Badari wrote: > Hi, > > Just want to give an update on the issue, hoping to get more thoughts/suggestions. > > I have been adding lot of debug to try to root cause the issue. > When I enabled CONFIG_VM_DEBUG, I run into following assertion failure: > > [ 1810.282055] entry: 0 folio: ffe6dfc30e428040 > [ 1810.282059] page dumped because: VM_BUG_ON_PAGE(entry != folio) > [ 1810.282062] BUG: kernel NULL pointer dereference, address: 0000000000000000 > [ 1810.282084] #PF: supervisor read access in kernel mode > [ 1810.282095] #PF: error_code(0x0000) - not-present page > [ 1810.282104] PGD 0 > [ 1810.282110] Oops: 0000 [#1] PREEMPT SMP NOPTI > [ 1810.282119] CPU: 86 PID: 15043 Comm: kdamond.1 Kdump: loaded Tainted: G S E 6.1.0-rc1+ #32 > [ 1810.282145] RIP: 0010:dump_page+0x25/0x340 > [ 1810.282156] Code: 0b cc cc cc cc 0f 1f 44 00 00 55 48 89 e5 41 57 49 89 ff 41 56 41 55 49 89 f5 41 54 53 48 83 ec 20 48 85 f6 0f 85 7d 72 ab 00 <49> 8b 07 48 83 f8 ff 0f 84 82 71 ab 00 49 8b 5f 08 f6 c3 01 0f 85 > [ 1810.282185] RSP: 0018:ff3fae02170637b8 EFLAGS: 00010046 > [ 1810.282193] RAX: 0000000000000033 RBX: ffe6dfc30e428040 RCX: 0000000000000002 > [ 1810.282204] RDX: 0000000000000000 RSI: ffffffffb85ad649 RDI: 00000000ffffffff > [ 1810.282215] RBP: ff3fae0217063800 R08: 0000000000000000 R09: c0000000fffeffff > [ 1810.282225] R10: 0000000000000001 R11: ff3fae0217063620 R12: 0000000000000001 > [ 1810.282234] R13: ffffffffb85c87e0 R14: 0000000000000000 R15: 0000000000000000 > [ 1810.282244] FS: 0000000000000000(0000) GS:ff25c2ea7e780000(0000) knlGS:0000000000000000 > [ 1810.282255] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 1810.282264] CR2: 0000000000000000 CR3: 000000552f40a006 CR4: 0000000000771ee0 > [ 1810.282274] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 1810.282284] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400 > [ 1810.282293] PKRU: 55555554 > [ 1810.282299] Call Trace: > [ 1810.282304] <TASK> > [ 1810.282310] __delete_from_swap_cache.cold.20+0x33/0x35 > [ 1810.282321] delete_from_swap_cache+0x50/0xa0 > [ 1810.282330] folio_free_swap+0xab/0xe0 > [ 1810.282339] free_swap_cache+0x8a/0xa0 > [ 1810.282346] free_page_and_swap_cache+0x12/0xb0 > [ 1810.282356] split_huge_page_to_list+0xf13/0x10d0 <<<<<<<<<<<<<<<<<< > [ 1810.282365] madvise_cold_or_pageout_pte_range+0x528/0x1390 > [ 1810.282374] walk_pgd_range+0x5fe/0xa10 > [ 1810.282383] __walk_page_range+0x184/0x190 > [ 1810.282391] walk_page_range+0x120/0x190 > [ 1810.282398] madvise_pageout+0x10b/0x2a0 > [ 1810.282406] ? set_track_prepare+0x48/0x70 > [ 1810.282415] madvise_vma_behavior+0x2f2/0xb10 > [ 1810.282422] ? find_vma_prev+0x72/0xc0 > [ 1810.282431] do_madvise+0x21b/0x440 > [ 1810.282439] damon_va_apply_scheme+0x76/0xa0 > [ 1810.282448] kdamond_fn+0xbe9/0xe10 > [ 1810.282456] ? damon_split_region_at+0x70/0x70 > [ 1810.282675] kthread+0xfc/0x130 > [ 1810.282837] ? kthread_complete_and_exit+0x20/0x20 > > Since I am not using hugepages explicitly.. I recompiled the kernel with > > CONFIG_TRANSPARENT_HUGEPAGE=n > > And my problem went away (including the original issue). For that one, please try with 6.1-rc3 (and CONFIG_TRANSPARENT_HUGEPAGE back to y). Mel put a fix to that kind of thing into 6.1-rc2, then I fixed its warning in 6.1-rc3 (git log -n2 mm/huge_memory.c tells more). Hugh
