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Thu, 06 Jul 2023 11:11:48 -0700 (PDT) MIME-Version: 1.0 References: <20230623164015.3431990-1-jiaqiyan@google.com> <20230623164015.3431990-2-jiaqiyan@google.com> <20230705233541.GC41006@monkey> In-Reply-To: <20230705233541.GC41006@monkey> From: Jiaqi Yan Date: Thu, 6 Jul 2023 11:11:37 -0700 Message-ID: Subject: Re: [PATCH v2 1/4] mm/hwpoison: delete all entries before traversal in __folio_free_raw_hwp To: Mike Kravetz Cc: naoya.horiguchi@nec.com, songmuchun@bytedance.com, shy828301@gmail.com, linmiaohe@huawei.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, duenwen@google.com, axelrasmussen@google.com, jthoughton@google.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 1A9CD80010 X-Stat-Signature: toqq13itp14ea3jbt51fwdcs98uxsumk X-HE-Tag: 1688667109-777901 X-HE-Meta: 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 zC/DD6iX B4L0H7TI7Jph9vCLbTjtwQuio6WgbUl3UayXx5DvaZ4JIJsUiySULVii7ZoIquzS/CeAWbr816TFTBh3ku0XpOjP/ojiOQOPPUG90Xz2AGr1rgZk0FR/CtwzAputBDVWm+pnwS8rm8eqCzrArShGYz0BZpaRnkaS/NF8ysz42aajoYMv2pXeUp3kCYENBi+vYKHMJnj+Lu/nQtTAhIDEhknWpK/gWob53vvcd7z0flZ3lgBkKKML2LBSKVN2IDZpjRJXSKsbPx9xKCBCdzKGgdFkZ2fgUbqBoxxZ+h8VFEYci1PMa9fX+K75oVQEGfJdJzU7/ 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: On Wed, Jul 5, 2023 at 4:36=E2=80=AFPM Mike Kravetz wrote: > > On 06/23/23 16:40, Jiaqi Yan wrote: > > Traversal on llist (e.g. llist_for_each_safe) is only safe AFTER entrie= s > > are deleted from the llist. > > > > llist_del_all are lock free with itself. folio_clear_hugetlb_hwpoison()= s > > from __update_and_free_hugetlb_folio and memory_failure won't need > > explicit locking when freeing the raw_hwp_list. > > > > Signed-off-by: Jiaqi Yan > > --- > > mm/memory-failure.c | 8 +++----- > > 1 file changed, 3 insertions(+), 5 deletions(-) > > After updating the reason for patch in commit message as suggested by Nao= ya, Thank you both Mike and Naoya! I will add the explanation in the next versi= on. > > Acked-by: Mike Kravetz > > -- > Mike Kravetz > > > > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > > index 004a02f44271..c415c3c462a3 100644 > > --- a/mm/memory-failure.c > > +++ b/mm/memory-failure.c > > @@ -1825,12 +1825,11 @@ static inline struct llist_head *raw_hwp_list_h= ead(struct folio *folio) > > > > static unsigned long __folio_free_raw_hwp(struct folio *folio, bool mo= ve_flag) > > { > > - struct llist_head *head; > > - struct llist_node *t, *tnode; > > + struct llist_node *t, *tnode, *head; > > unsigned long count =3D 0; > > > > - head =3D raw_hwp_list_head(folio); > > - llist_for_each_safe(tnode, t, head->first) { > > + head =3D llist_del_all(raw_hwp_list_head(folio)); > > + llist_for_each_safe(tnode, t, head) { > > struct raw_hwp_page *p =3D container_of(tnode, struct raw= _hwp_page, node); > > > > if (move_flag) > > @@ -1840,7 +1839,6 @@ static unsigned long __folio_free_raw_hwp(struct = folio *folio, bool move_flag) > > kfree(p); > > count++; > > } > > - llist_del_all(head); > > return count; > > } > > > > -- > > 2.41.0.162.gfafddb0af9-goog > >