rhashtable: Schedule async resize when sync realloc fails

When rhashtable_insert_rehash() fails with ENOMEM, this indicates that
we can't allocate the necessary memory in the current context but the
limits as set by the user would still allow to grow.

Thus attempt an async resize in the background where we can allocate
using GFP_KERNEL which is more likely to succeed. The insertion itself
will still fail to indicate pressure.

This fixes a bug where the table would never continue growing once the
utilization is above 100%.

Fixes: ccd57b1bd324 ("rhashtable: Add immediate rehash during insertion")
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 4898442b837fbd715f8d5079a1060e43c4b7a367..f648cfde852036f10338a5c905746c43007441e5 100644 (file)
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -410,8 +410,13 @@ int rhashtable_insert_rehash(struct rhashtable *ht)
                return -EBUSY;
 
        new_tbl = bucket_table_alloc(ht, size, GFP_ATOMIC);
-       if (new_tbl == NULL)
+       if (new_tbl == NULL) {
+               /* Schedule async resize/rehash to try allocation
+                * non-atomic context.
+                */
+               schedule_work(&ht->run_work);
                return -ENOMEM;
+       }
 
        err = rhashtable_rehash_attach(ht, tbl, new_tbl);
        if (err) {