Re: Reproducable(?) kernel panic

[Andrew Doran <ad%netbsd.org@localhost>]

On Wed, Jan 22, 2020 at 10:41:15AM +0100, Martin Husemann wrote:

> I have a dying disk on my evbearmv7hf-eb machine and am trying to get a
> good-enough backup. Any write activity on this disk is ... bad.
> 
> So I booted single user, manualy set up a bit of networking and NFS-mounted
> a filesystem on /mnt, then ran:
> 
>   tar -cf - --one-file-system / | gzip -9 > /mnt/backup.tgz
> 
> and this worked for quite some time (luckily enough w/o disk read errors)
> but then crashed:
> 
> 
> [ 3443.7195495] Reader / writer lock error: rw_vector_enter,353: locking against myself
> [ 3443.7195495] lock address : 0x0000000080ac72d4
> [ 3443.7195495] current cpu  :                  0
> [ 3443.7195495] current lwp  : 0x0000000092e17a00
> [ 3443.7487010] owner/count  : 0x0000000092e17a00 flags    : 0x0000000000000004
> [ 3443.7487010] panic: lock error: Reader / writer lock: rw_vector_enter,353: locking against myself: lock 0x80ac72d4 cpu 0 lwp 0x92e17a00
> [ 3443.7678914] cpu0: Begin traceback...
> [ 3443.7678914] 0x9bdccf14: netbsd:db_panic+0x14
> [ 3443.7678914] 0x9bdccf2c: netbsd:vpanic+0x170
> [ 3443.7790247] 0x9bdccf44: netbsd:snprintf
> [ 3443.7790247] 0x9bdccf84: netbsd:filt_logread
> [ 3443.7882661] 0x9bdccf9c: netbsd:rw_abort+0x3c
> [ 3443.7882661] 0x9bdcd014: netbsd:rw_enter+0x3f8
> [ 3443.7998323] 0x9bdcd16c: netbsd:uvm_fault_internal+0x128
> [ 3443.7998323] 0x9bdcd23c: netbsd:data_abort_handler+0x1a0
> [ 3443.8105868] 0x9bdcd304: netbsd:address_exception_entry+0x5c
> [ 3443.8199030] 0x9bdcd374: netbsd:uvm_map_prepare+0x1e4

That is surprising, nothing has changed there recently.  Does it always
crash there?  Any idea what line uvm_map_prepare+0x1e4 is?

Anrew

> [ 3443.8199030] 0x9bdcd3e4: netbsd:uvm_map+0x8c
> [ 3443.8302046] 0x9bdcd454: netbsd:uvm_km_alloc+0xd8
> [ 3443.8302046] 0x9bdcd4a4: netbsd:pool_grow+0x68
> [ 3443.8410680] 0x9bdcd4bc: netbsd:pool_catchup.part.20+0x30
> [ 3443.8410680] 0x9bdcd514: netbsd:pool_get+0x60c
> [ 3443.8510863] 0x9bdcd55c: netbsd:allocbuf+0xe8
> [ 3443.8510863] 0x9bdcd594: netbsd:getblk+0x164
> [ 3443.8610743] 0x9bdcd664: netbsd:ufs_bmaparray+0x1a8
> [ 3443.8610743] 0x9bdcd68c: netbsd:ufs_bmap+0x68
> [ 3443.8710820] 0x9bdcd6cc: netbsd:VOP_BMAP+0x70
> [ 3443.8710820] 0x9bdcd84c: netbsd:genfs_getpages+0x1258
> [ 3443.8810791] 0x9bdcd894: netbsd:VOP_GETPAGES+0x70
> [ 3443.8810791] 0x9bdcd8fc: netbsd:ra_startio+0x110
> [ 3443.8914038] 0x9bdcd94c: netbsd:uvm_ra_request+0x128
> [ 3443.8914038] 0x9bdcd9a4: netbsd:uvn_get+0x11c
> [ 3443.9031380] 0x9bdcda3c: netbsd:ubc_fault+0x204
> [ 3443.9114156] 0x9bdcdb94: netbsd:uvm_fault_internal+0x588
> [ 3443.9114156] 0x9bdcdc64: netbsd:data_abort_handler+0x1a0
> 
> 
> I tried again and it crashed again :-)
> 
> This is with latest current from a few hours ago.
> 
> Martin