Memory allocation failures print backtraces by default, but when we're
running out of a rhashtable worker the backtrace is useless - it doesn't
tell us which hashtable the allocation failure was for.

This adds a dedicated warning that prints out functions from the
rhashtable params, which will be a bit more useful.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Thomas Graf <tgraf@suug.ch>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
---
 lib/rhashtable.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 6ae2ba8e06a2..d3fce9c8989a 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -360,9 +360,14 @@ static int rhashtable_rehash_alloc(struct rhashtable *ht,
 
 	ASSERT_RHT_MUTEX(ht);
 
-	new_tbl = bucket_table_alloc(ht, size, GFP_KERNEL);
-	if (new_tbl == NULL)
+	new_tbl = bucket_table_alloc(ht, size, GFP_KERNEL|__GFP_NOWARN);
+	if (new_tbl == NULL) {
+		WARN("rhashtable bucket table allocation failure for %ps",
+		     (void *) ht->p.hashfn ?:
+		     (void *) ht->p.obj_hashfn ?:
+		     (void *) ht->p.obj_cmpfn);
 		return -ENOMEM;
+	}
 
 	err = rhashtable_rehash_attach(ht, old_tbl, new_tbl);
 	if (err)
-- 
2.42.0

On Wed, Nov 22, 2023 at 06:32:16PM -0500, Kent Overstreet wrote:
> Memory allocation failures print backtraces by default, but when we're
> running out of a rhashtable worker the backtrace is useless - it doesn't
> tell us which hashtable the allocation failure was for.
> 
> This adds a dedicated warning that prints out functions from the
> rhashtable params, which will be a bit more useful.
> 
> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
> Cc: Thomas Graf <tgraf@suug.ch>
> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> ---
>  lib/rhashtable.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>

However, you'll need to repost this via netdev@vger.kernel.org for
it to be merged.

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

On Thu, Nov 23, 2023 at 04:32:47PM +0800, Herbert Xu wrote:
> On Wed, Nov 22, 2023 at 06:32:16PM -0500, Kent Overstreet wrote:
> > Memory allocation failures print backtraces by default, but when we're
> > running out of a rhashtable worker the backtrace is useless - it doesn't
> > tell us which hashtable the allocation failure was for.
> > 
> > This adds a dedicated warning that prints out functions from the
> > rhashtable params, which will be a bit more useful.
> > 
> > Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
> > Cc: Thomas Graf <tgraf@suug.ch>
> > Cc: Herbert Xu <herbert@gondor.apana.org.au>
> > ---
> >  lib/rhashtable.c | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
> 
> However, you'll need to repost this via netdev@vger.kernel.org for
> it to be merged.

Thanks!