Re: svn commit: r366997 - head/sys/kern
In message <20201024172452.gd2...@kib.kiev.ua>, Konstantin Belousov writes: > On Sat, Oct 24, 2020 at 01:30:37PM +, Mateusz Guzik wrote: > > Author: mjg > > Date: Sat Oct 24 13:30:37 2020 > > New Revision: 366997 > > URL: https://svnweb.freebsd.org/changeset/base/366997 > > > > Log: > > vfs: fix a race where reclaim vholds freed vnodes > A description of the race in the commit message would be respectful to > other readers of the code, so that we do not need to reverse-eng the > change to understand what and why was fixed. +1 -- Cheers, Cy Schubert FreeBSD UNIX: Web: https://FreeBSD.org NTP: Web: https://nwtime.org The need of the many outweighs the greed of the few. ___ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
Re: svn commit: r366997 - head/sys/kern
On Sat, Oct 24, 2020 at 01:30:37PM +, Mateusz Guzik wrote: > Author: mjg > Date: Sat Oct 24 13:30:37 2020 > New Revision: 366997 > URL: https://svnweb.freebsd.org/changeset/base/366997 > > Log: > vfs: fix a race where reclaim vholds freed vnodes A description of the race in the commit message would be respectful to other readers of the code, so that we do not need to reverse-eng the change to understand what and why was fixed. > > Reported by:pho > Tested by: pho (previous version) > Fixes: r366974 ("vfs: stop taking the interlock in vnode reclaim") > > Modified: > head/sys/kern/vfs_subr.c > > Modified: head/sys/kern/vfs_subr.c > == > --- head/sys/kern/vfs_subr.c Sat Oct 24 13:16:10 2020(r366996) > +++ head/sys/kern/vfs_subr.c Sat Oct 24 13:30:37 2020(r366997) > @@ -109,6 +109,7 @@ static void syncer_shutdown(void *arg, int howto); > static int vtryrecycle(struct vnode *vp); > static void v_init_counters(struct vnode *); > static void vgonel(struct vnode *); > +static bool vhold_recycle(struct vnode *); > static void vfs_knllock(void *arg); > static void vfs_knlunlock(void *arg); > static void vfs_knl_assert_locked(void *arg); > @@ -1126,7 +1127,8 @@ restart: > goto next_iter; > } > > - vhold(vp); > + if (!vhold_recycle(vp)) > + goto next_iter; > TAILQ_REMOVE(_list, mvp, v_vnodelist); > TAILQ_INSERT_AFTER(_list, vp, mvp, v_vnodelist); > mtx_unlock(_list_mtx); > @@ -1231,7 +1233,8 @@ restart: > if (__predict_false(vp->v_type == VBAD || vp->v_type == VNON)) { > continue; > } > - vhold(vp); > + if (!vhold_recycle(vp)) > + continue; > count--; > mtx_unlock(_list_mtx); > vtryrecycle(vp); > @@ -3248,13 +3251,11 @@ vholdnz(struct vnode *vp) > * However, while this is more performant, it hinders debugging by > eliminating > * the previously mentioned invariant. > */ > -bool > -vhold_smr(struct vnode *vp) > +static bool __always_inline > +_vhold_cond(struct vnode *vp) > { > int count; > > - VFS_SMR_ASSERT_ENTERED(); > - > count = atomic_load_int(>v_holdcnt); > for (;;) { > if (count & VHOLD_NO_SMR) { > @@ -3270,6 +3271,28 @@ vhold_smr(struct vnode *vp) > return (true); > } > } > +} > + > +bool > +vhold_smr(struct vnode *vp) > +{ > + > + VFS_SMR_ASSERT_ENTERED(); > + return (_vhold_cond(vp)); > +} > + > +/* > + * Special case for vnode recycling. > + * > + * Vnodes are present on the global list until UMA takes them out. > + * Attempts to recycle only need the relevant lock and have no use for SMR. > + */ > +static bool > +vhold_recycle(struct vnode *vp) > +{ > + > + mtx_assert(_list_mtx, MA_OWNED); > + return (_vhold_cond(vp)); > } > > static void __noinline ___ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
svn commit: r366997 - head/sys/kern
Author: mjg Date: Sat Oct 24 13:30:37 2020 New Revision: 366997 URL: https://svnweb.freebsd.org/changeset/base/366997 Log: vfs: fix a race where reclaim vholds freed vnodes Reported by: pho Tested by:pho (previous version) Fixes:r366974 ("vfs: stop taking the interlock in vnode reclaim") Modified: head/sys/kern/vfs_subr.c Modified: head/sys/kern/vfs_subr.c == --- head/sys/kern/vfs_subr.cSat Oct 24 13:16:10 2020(r366996) +++ head/sys/kern/vfs_subr.cSat Oct 24 13:30:37 2020(r366997) @@ -109,6 +109,7 @@ static void syncer_shutdown(void *arg, int howto); static int vtryrecycle(struct vnode *vp); static voidv_init_counters(struct vnode *); static voidvgonel(struct vnode *); +static boolvhold_recycle(struct vnode *); static voidvfs_knllock(void *arg); static voidvfs_knlunlock(void *arg); static voidvfs_knl_assert_locked(void *arg); @@ -1126,7 +1127,8 @@ restart: goto next_iter; } - vhold(vp); + if (!vhold_recycle(vp)) + goto next_iter; TAILQ_REMOVE(_list, mvp, v_vnodelist); TAILQ_INSERT_AFTER(_list, vp, mvp, v_vnodelist); mtx_unlock(_list_mtx); @@ -1231,7 +1233,8 @@ restart: if (__predict_false(vp->v_type == VBAD || vp->v_type == VNON)) { continue; } - vhold(vp); + if (!vhold_recycle(vp)) + continue; count--; mtx_unlock(_list_mtx); vtryrecycle(vp); @@ -3248,13 +3251,11 @@ vholdnz(struct vnode *vp) * However, while this is more performant, it hinders debugging by eliminating * the previously mentioned invariant. */ -bool -vhold_smr(struct vnode *vp) +static bool __always_inline +_vhold_cond(struct vnode *vp) { int count; - VFS_SMR_ASSERT_ENTERED(); - count = atomic_load_int(>v_holdcnt); for (;;) { if (count & VHOLD_NO_SMR) { @@ -3270,6 +3271,28 @@ vhold_smr(struct vnode *vp) return (true); } } +} + +bool +vhold_smr(struct vnode *vp) +{ + + VFS_SMR_ASSERT_ENTERED(); + return (_vhold_cond(vp)); +} + +/* + * Special case for vnode recycling. + * + * Vnodes are present on the global list until UMA takes them out. + * Attempts to recycle only need the relevant lock and have no use for SMR. + */ +static bool +vhold_recycle(struct vnode *vp) +{ + + mtx_assert(_list_mtx, MA_OWNED); + return (_vhold_cond(vp)); } static void __noinline ___ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"