Re: LTP: fork13: kernel panic on rk3399-rock-pi-4 running mainline 6.10.rc3

[Baolin Wang]

On 2024/6/11 20:09, David Hildenbrand wrote:
> On 11.06.24 13:39, Baolin Wang wrote:
> > On 2024/6/11 18:32, David Hildenbrand wrote:
> > > On 11.06.24 12:14, Naresh Kamboju wrote:
> > > > The kernel panic was noticed while running LTP syscalls fork13 (long
> > > > running) on
> > > > the mainline master 6.10.rc3 kernel on arm64 rk3399-rock-pi-4 device.
> > > >
> > > > Please find detailed logs in the links,
> > > >
> > > > As you know fork13 is a stress test case trying to generate a maximum
> > > > number
> > > > of PID's in a 100,000 loop.
> > > >
> > > > This device is running via NFS mounted filesystem.
> > > >
> > > > I have tried to reproduce this problem in a loop but failed to
> > > > reproduce the
> > > > crash.
> > > >
> > > >
> > > > Crash flow:
> > > > ------
> > > > fork13 run started
> > > > BUG: Bad page map in process fork13
> > > > BUG: Bad rss-counter state mm:
> > > > Unable to handle kernel paging request at virtual address
> > > > Internal error: Oops: 0000000096000046
> > > > run for 800 secs ( 13 minutes) and more.
> > > > fork14 run started and completed
> > > >
> > > > fpathconf01 run started and completed
> > > > sugov:
> > > >
> > > > Unable to handle kernel NULL pointer dereference at virtual address
> > > >
> > > > Insufficient stack space to handle exception!
> > > > end Kernel panic - not syncing: kernel stack overflow
> > > >
> > > > I have tried to decode stack dump by not being useful [1].
> > > > [1] https://people.linaro.org/~naresh.kamboju/output-rk3399.txt
> > > >
> > > > Test log :
> > > > --------
> > > > tst_test.c:1733: TINFO: LTP version: 20240524
> > > > tst_test.c:1617: TINFO: Timeout per run is 0h 15m 00s
> > > > [  904.280569] BUG: Bad page map in process fork13  pte:2000000019ffc3
> > > > pmd:80000000df55003
> > > > [  904.281397] page: refcount:1 mapcount:-1 mapping:0000000000000000
> > > > index:0x0 pfn:0x19f
> > >
> > > Mapcount underflow on a small folio (head: not printed).
> > >
> > > [...]
> > >
> > > > [  904.294564] BUG: Bad page map in process fork13  pte:200000002e4fc3
> > > > pmd:80000000df55003
> > > > [  904.295275] page: refcount:2 mapcount:-1 mapping:000000007885152f
> > > > index:0x6 pfn:0x2e4
> > >
> > > Another mapcount underflow on a small folio (head: not printed).
> > >
> > >
> > > > [  904.309309] BUG: Bad page map in process fork13  pte:20000000cc6fc3
> > > > pmd:80000000df55003
> > > > [  904.310031] page: refcount:1 mapcount:-1 mapping:0000000000000000
> > > > index:0x6 pfn:0xcc6
> > > > [  904.310728] head: order:3 mapcount:-1 entire_mapcount:0
> > > > nr_pages_mapped:8388607 pincount:0
> > >
> > > Mapcount underflow on a large folio.
> > >
> > > ...
> > >
> > > > [  904.326666] BUG: Bad page map in process fork13  pte:20000000268fc3
> > > > pmd:80000000df55003
> > > > [  904.327390] page: refcount:1 mapcount:-1 mapping:00000000f0624181
> > > > index:0x1b pfn:0x268
> > >
> > > Another mapcount underflow on a small folio (head: not printed).
> > >
> > > > [  904.328094] memcg:ffff0000016b4000
> > > > [  904.328401] aops:nfs_file_aops ino:8526e6 dentry
> > > > name:"libgpg-error.so.0.36.0"
> > > > [  904.329051] flags:
> > > > 0x3fffe000000002c(referenced|uptodate|lru|node=0|zone=0|lastcpupid=0x1ffff)
> > > > [  904.329878] raw: 03fffe000000002c fffffdffc0009a48 fffffdffc022f3c8
> > > > ffff00000688bd60
> > > > [  904.330561] raw: 000000000000001b 0000000000000000 00000001fffffffe
> > > > ffff0000016b4000
> > > > [  904.331240] page dumped because: bad pte
> > > > [  904.331590] addr:0000aaaad9afe000 vm_flags:00000075
> > > > anon_vma:0000000000000000 mapping:ffff0000300d4188 index:2e
> > > > [  904.332476] file:fork13 fault:filemap_fault mmap:nfs_file_mmap
> > > > read_folio:nfs_read_folio
> > > > [  904.333245] CPU: 5 PID: 22685 Comm: fork13 Tainted: G    B
> > >
> > >
> > > Are these maybe side-effects due to
> > >
> > > https://lkml.kernel.org/r/20240607103241.1298388-1-wangkefeng.wang@xxxxxxxxxx
> >
> > IIUC, the rk3399-rock-pi-4b device has no NUMA nodes (6 arm64 cores), so
> > I don't think the numa balancing will cause this issue.
> >
> > Anyway, I will run fork13 test case on my arm64 server to try.
>
> I have the faint recollection that we can (or at least could in the 
> past) end up in do_numa_page() also without NUMA hinting.
>
> I documented in 51d3d5eb74ff53b92dcff48b30ae2ed8edd85a32:
>
> "
> Note that do_numa_page() / do_huge_pmd_numa_page() can be reached even
> without NUMA hinting (which currently doesn't seem to be applicable to
> shmem), for example, by using uffd-wp with a PROT_WRITE shmem VMA.
> "

I see. Thanks for explanation.