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Tue, 26 Aug 2025 19:12:22 -0700 (PDT) MIME-Version: 1.0 References: <20250826231626.218675-1-max.kellermann@ionos.com> <20250826231626.218675-2-max.kellermann@ionos.com> In-Reply-To: From: Chris Li Date: Tue, 26 Aug 2025 19:12:10 -0700 X-Gmail-Original-Message-ID: X-Gm-Features: Ac12FXyA8McbAPcgcSwRJ4XPhqPTQ1ZXjfdNh9v53BJi2bHEYOaY-70OWXZymKE Message-ID: Subject: Re: [PATCH 2/2] mm/swap: add BUG_ON(folio==NULL) to folios_put_refs() To: Zi Yan Cc: Max Kellermann , akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, shikemeng@huaweicloud.com, kasong@tencent.com, nphamcs@gmail.com, bhe@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 6E31A100005 X-Stat-Signature: aqaw7t7pffdd7t7gow9owj6txodmadsr X-Rspam-User: X-HE-Tag: 1756260744-678710 X-HE-Meta: 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 lNtxqQu7 nRkPDRkE8JJw3oKKbID+5FJMJ2TVvwPLvWJUO X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Aug 26, 2025 at 6:43=E2=80=AFPM Zi Yan wrote: > > --- a/mm/swap.c > > +++ b/mm/swap.c > > @@ -952,6 +952,7 @@ void folios_put_refs(struct folio_batch *folios, un= signed int *refs) > > for (i =3D 0, j =3D 0; i < folios->nr; i++) { > > struct folio *folio =3D folios->folios[i]; > > unsigned int nr_refs =3D refs ? refs[i] : 1; > > + BUG_ON(folio =3D=3D NULL); > > > > if (is_huge_zero_folio(folio)) > > continue; > > We are moving away from BUG_ON. It is better to use WARN_ON_ONCE and skip > NULL values: > > if (WARN_ON_ONCE(!folio)) > continue; +1 Chris