On 22/10/23(Sun) 20:29, Miod Vallat wrote:
> > On 21/10/23(Sat) 14:28, Miod Vallat wrote:
> > > > Stuart, Miod, I wonder if this also help for the off-by-one issue you
> > > > are seeing. It might not.
> > >
> > > It makes the aforementioned issue disappear on the affected machine.
> >
> > Thanks at lot for testing!
>
> Spoke too soon. I have just hit
>
> panic: kernel diagnostic assertion "uvmexp.swpgonly > 0" failed: file
> "/usr/src/sys/uvm/uvm_anon.c", line 121
> Stopped at db_enter+0x8: add #0x4, r14
> TID PID UID PRFLAGS PFLAGS CPU COMMAND
> *235984 11904 0 0x14000 0x200 0 reaper
> db_enter() at db_enter+0x8
> panic() at panic+0x74
> __assert() at __assert+0x1c
> uvm_anfree_list() at uvm_anfree_list+0x156
> amap_wipeout() at amap_wipeout+0xe6
> uvm_unmap_detach() at uvm_unmap_detach+0x42
> uvm_map_teardown() at uvm_map_teardown+0x104
> uvmspace_free() at uvmspace_free+0x2a
> reaper() at reaper+0x86
> ddb> show uvmexp
> Current UVM status:
> pagesize=4096 (0x1000), pagemask=0xfff, pageshift=12
> 14875 VM pages: 376 active, 2076 inactive, 1 wired, 7418 free (924
> zero)
> min 10% (25) anon, 10% (25) vnode, 5% (12) vtext
> freemin=495, free-target=660, inactive-target=2809, wired-max=4958
> faults=73331603, traps=39755714, intrs=33863551, ctxswitch=11641480
> fpuswitch
> =0
> softint=15742561, syscalls=39755712, kmapent=11
> fault counts:
> noram=1, noanon=0, noamap=0, pgwait=1629, pgrele=0
> ok relocks(total)=1523991(1524022), anget(retries)=23905247(950233),
> amapco
> py=9049749
> neighbor anon/obj pg=12025732/40041442,
> gets(lock/unlock)=12859247/574102
> cases: anon=20680175, anoncow=3225049, obj=11467884, prcopy=1391019,
> przero
> =36545783
> daemon and swap counts:
> woke=6868, revs=6246, scans=3525644, obscans=511526, anscans=2930634
> busy=0, freed=1973275, reactivate=83484, deactivate=3941988
> pageouts=94506, pending=94506, nswget=949421
> nswapdev=1
> swpages=4194415, swpginuse=621, swpgonly=0 paging=0
> kernel pointers:
> objs(kern)=0x8c3ca94c
I wonder if the diff below makes a difference. It's hard to debug and it
might be worth adding a counter for bad swap slots.
Index: uvm/uvm_anon.c
===================================================================
RCS file: /cvs/src/sys/uvm/uvm_anon.c,v
retrieving revision 1.56
diff -u -p -r1.56 uvm_anon.c
--- uvm/uvm_anon.c 2 Sep 2023 08:24:40 -0000 1.56
+++ uvm/uvm_anon.c 22 Oct 2023 21:27:42 -0000
@@ -116,7 +116,7 @@ uvm_anfree_list(struct vm_anon *anon, st
uvm_unlock_pageq(); /* free the daemon */
}
} else {
- if (anon->an_swslot != 0) {
+ if (anon->an_swslot != 0 && anon->an_swslot != SWSLOT_BAD) {
/* This page is no longer only in swap. */
KASSERT(uvmexp.swpgonly > 0);
atomic_dec_int(&uvmexp.swpgonly);
