| Message ID | 1440071002-19085-2-git-send-email-vbabka@suse.cz (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu 20-08-15 13:43:21, Vlastimil Babka wrote: > Perform the same debug checks in alloc_pages_node() as are done in > __alloc_pages_node(), by making the former function a wrapper of the latter > one. > > In addition to better diagnostics in DEBUG_VM builds for situations which > have been already fatal (e.g. out-of-bounds node id), there are two visible > changes for potential existing buggy callers of alloc_pages_node(): > > - calling alloc_pages_node() with any negative nid (e.g. due to arithmetic > overflow) was treated as passing NUMA_NO_NODE and fallback to local node was > applied. This will now be fatal. OK, this is sensible > - calling alloc_pages_node() with an offline node will now be checked for > DEBUG_VM builds. Since it's not fatal if the node has been previously online, > and this patch may expose some existing buggy callers, change the VM_BUG_ON > in __alloc_pages_node() to VM_WARN_ON. Yes, bugging on just because we race with memory hotplug or use stale node number is not appropriate because the fallback is straightforward. A warning should help to identify and fix those place. > > Signed-off-by: Vlastimil Babka <vbabka@suse.cz> > Acked-by: David Rientjes <rientjes@google.com> > Acked-by: Johannes Weiner <hannes@cmpxchg.org> > Acked-by: Christoph Lameter <cl@linux.com> > --- > include/linux/gfp.h | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index d2c142b..4a12cae2 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -310,23 +310,23 @@ __alloc_pages(gfp_t gfp_mask, unsigned int order, > static inline struct page * > __alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order) > { > - VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES || !node_online(nid)); > + VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES); > + VM_WARN_ON(!node_online(nid)); > > return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask)); > } > > /* > * Allocate pages, preferring the node given as nid. When nid == NUMA_NO_NODE, > - * prefer the current CPU's node. > + * prefer the current CPU's node. Otherwise node must be valid and online. > */ > static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask, > unsigned int order) > { > - /* Unknown node is current node */ > - if (nid < 0) > + if (nid == NUMA_NO_NODE) > nid = numa_node_id(); > > - return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask)); > + return __alloc_pages_node(nid, gfp_mask, order); > } > > #ifdef CONFIG_NUMA > -- > 2.5.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
On Thu 20-08-15 16:14:34, Michal Hocko wrote: > On Thu 20-08-15 13:43:21, Vlastimil Babka wrote: > > Perform the same debug checks in alloc_pages_node() as are done in > > __alloc_pages_node(), by making the former function a wrapper of the latter > > one. > > > > In addition to better diagnostics in DEBUG_VM builds for situations which > > have been already fatal (e.g. out-of-bounds node id), there are two visible > > changes for potential existing buggy callers of alloc_pages_node(): > > > > - calling alloc_pages_node() with any negative nid (e.g. due to arithmetic > > overflow) was treated as passing NUMA_NO_NODE and fallback to local node was > > applied. This will now be fatal. > > OK, this is sensible > > > - calling alloc_pages_node() with an offline node will now be checked for > > DEBUG_VM builds. Since it's not fatal if the node has been previously online, > > and this patch may expose some existing buggy callers, change the VM_BUG_ON > > in __alloc_pages_node() to VM_WARN_ON. > > Yes, bugging on just because we race with memory hotplug or use > stale node number is not appropriate because the fallback is > straightforward. A warning should help to identify and fix those place. > > > > > Signed-off-by: Vlastimil Babka <vbabka@suse.cz> > > Acked-by: David Rientjes <rientjes@google.com> > > Acked-by: Johannes Weiner <hannes@cmpxchg.org> > > Acked-by: Christoph Lameter <cl@linux.com> Forgot to add Acked-by: Michal Hocko <mhocko@suse.com>
diff --git a/include/linux/gfp.h b/include/linux/gfp.h index d2c142b..4a12cae2 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -310,23 +310,23 @@ __alloc_pages(gfp_t gfp_mask, unsigned int order, static inline struct page * __alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order) { - VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES || !node_online(nid)); + VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES); + VM_WARN_ON(!node_online(nid)); return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask)); } /* * Allocate pages, preferring the node given as nid. When nid == NUMA_NO_NODE, - * prefer the current CPU's node. + * prefer the current CPU's node. Otherwise node must be valid and online. */ static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order) { - /* Unknown node is current node */ - if (nid < 0) + if (nid == NUMA_NO_NODE) nid = numa_node_id(); - return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask)); + return __alloc_pages_node(nid, gfp_mask, order); } #ifdef CONFIG_NUMA