On Wed, Nov 25, 2020 at 1:54 PM Jason Baron <jbaron@xxxxxxxxxx> wrote: > > > > On 11/25/20 2:36 PM, Jim Cromie wrote: > > In ddebug_putsite(), dont zs_unmap the callsite if it is enabled for > > printing. This means that the next time this pr_debug callsite is > > executed, the _getsite() will succeed quickly without remapping the > > zrec. > > > > Once the callsite is disabled via >control, a following _putsite() > > will see the flag cleared, and zs_unmap it. > > > > This changes the lifetime of our zs_mappings from brief (only for the > > single printk) to as long as uptime (if a prdebug is enabled til > > poweroff). This appears to be triggering the ensuing mayhem. > > > > I am able to get through init, to root console, by disabling all > > dynamic-debugs, including the ones that are enabled at compile. > > > > $ kruna --kopt \*.dyndbg=-p --kopt debug_locks_proceed=1 > > > > but enabling any pr-debug crashes. > > Plain old boot also panics, as pasted below. > > > > > Hi Jim, > > Looks like you've made a lot of progress with this series...but if I > understand correctly there are still some unresolved issues (panic). > So I think this series is more 'RFC' at this point? > yes, RFC. WIP suggests I know whats needed next. certainly Ive seen a variety of sleeping while atomic ... BUGs, > I was also expecting to see updates to the actual printing functions > to now use dp->site. But perhaps I missed those bits? those bits were changed in patch 5 basically changes are ~ s/dp/dc/g, and in ddebug_getsite / _putsite > > Thanks, > > -Jason > > > $ kruna --kopt debug_locks_proceed=1 > > [ 1.915768] ? rest_init+0x24d/0x24d > > [ 1.916417] kernel_init+0xaf/0x103 > > [ 1.917038] ret_from_fork+0x22/0x30 > > [ 1.917726] Kernel Offset: disabled > > [ 1.918324] ---[ end Kernel panic - not syncing: Requested init /bin/sh failed (error -14). ]--- > > QEMU 5.1.0 monitor - type 'help' for more information > > > > Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx> > > --- > > lib/dynamic_debug.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c > > index 534d73e45844..0c69aa52395d 100644 > > --- a/lib/dynamic_debug.c > > +++ b/lib/dynamic_debug.c > > @@ -165,7 +165,9 @@ static void ddebug_putsite(struct _ddebug *dp) > > /* need to keep site until zmap backing exists */ > > return; > > > > - /* always unmap for now. if !pr-debug has locking issues */ > > + if (dp->flags & _DPRINTK_FLAGS_PRINT) > > + return; /* keep maps of enabled pr_debugs */ > > + > > zs_unmap_object(dd_callsite_zpool, dp->zhandle); > > dp->site = NULL; > > } > >
