On 29. 04. 19, 10:16, Jiri Slaby wrote: > Hi, > > with new enough systemd, one of our systems 100% crashes during boot. > Kernels I tried are all affected: 5.1-rc7, 5.0.10 stable, 4.12.14. > > The 5.1-rc7 crash: >> [ 12.022637] systemd[1]: Starting Create list of required static device nodes for the current kernel... >> [ 12.023353] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 >> [ 12.041502] #PF error: [normal kernel read fault] >> [ 12.041502] PGD 0 P4D 0 >> [ 12.041502] Oops: 0000 [#1] SMP NOPTI >> [ 12.041502] CPU: 0 PID: 208 Comm: (kmod) Not tainted 5.1.0-rc7-1.g04c1966-default #1 openSUSE Tumbleweed (unreleased) >> [ 12.041502] Hardware name: Supermicro H8DSP-8/H8DSP-8, BIOS 080011 06/30/2006 >> [ 12.041502] RIP: 0010:list_lru_add+0x94/0x170 >> [ 12.041502] Code: c6 07 00 66 66 66 90 31 c0 5b 5d 41 5c 41 5d 41 5e 41 5f c3 49 8b 7c 24 20 49 8d 54 24 08 48 85 ff 74 07 e9 46 00 00 00 31 ff <48> 8b 42 08 4c 89 6a 08 49 89 55 00 49 89 45 08 4c 89 28 48 8b 42 >> [ 12.041502] RSP: 0018:ffffb11b8091be50 EFLAGS: 00010202 >> [ 12.041502] RAX: 0000000000000001 RBX: ffff930b35705a40 RCX: ffff9309cf21ade0 >> [ 12.041502] RDX: 0000000000000000 RSI: ffff930ab61bc587 RDI: ffff930a17711000 >> [ 12.041502] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 >> [ 12.041502] R10: 0000000000000000 R11: 0000000000000008 R12: ffff9309f5f86640 >> [ 12.041502] R13: ffff930ab5705a40 R14: 0000000000000001 R15: ffff930a171dc4e0 >> [ 12.041502] FS: 00007f42d6ea5940(0000) GS:ffff930ab7800000(0000) knlGS:0000000000000000 >> [ 12.041502] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> [ 12.041502] CR2: 0000000000000008 CR3: 0000000057dec000 CR4: 00000000000006f0 >> [ 12.041502] Call Trace: >> [ 12.041502] d_lru_add+0x44/0x50 ... > and even makes the beast booting. memcg has very wrong assumptions on > 'memcg_nr_cache_ids'. It does not assume it can change later, despite it > does. ... > I am not sure why this is machine-dependent. I cannot reproduce on any > other box. > > Any idea how to fix this mess? memcg_update_all_list_lrus should take care about resizing the array. So it looks like list_lru_from_memcg_idx returns a stale pointer to list_lru_from_kmem and then to list_lru_add. Still investigating. thanks, -- js suse labs
