> From here it goes down (with flags == PGO_CLEANIT|PGO_FREE) as
> 
>     uobj->pgops->pgo_put -> uvn_put -> VOP_PUTPAGES -> genfs_putpages
> 
> Here genfs_putpages is allowed to sleep because flags has PGO_CLEANIT.
> This would put uvmpd_scan_inactive() to sleep if there is a suspension on
> this vnode leading to out-of-memory deadlocks.
> 
> To avoid it we start a FSTRANS_NOWAIT transaction here.
> This way we will either succeed and have a valid transaction or
> we simply skip this page and try the next one.

you can do "if (pagedaemon)" in putpages.

YAMAMOTO Takashi