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From: Naoya Horiguchi To: Jiaqi Yan Cc: mike.kravetz@oracle.com, 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 Subject: Re: [PATCH v2 1/4] mm/hwpoison: delete all entries before traversal in __folio_free_raw_hwp Message-ID: <20230630145217.GA2213127@ik1-406-35019.vs.sakura.ne.jp> References: <20230623164015.3431990-1-jiaqiyan@google.com> <20230623164015.3431990-2-jiaqiyan@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230623164015.3431990-2-jiaqiyan@google.com> X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: A07A7140010 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: 5oipc6t18a1n1ieg31pigx34etbnd6tg X-HE-Tag: 1688136748-516503 X-HE-Meta: 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 BuhBrG64 nkgJCojUtwfmro73Oab/nMgfIukIcS21J2acI44/N6X2uetrAh+G/rAoHfBa9yk0SwIl4yPf0b1FL3IqIef+gnoldxx5JFVbA6tDKvJFQdv4wQEdnAezkj0MazQ== 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 Fri, Jun 23, 2023 at 04:40:12PM +0000, Jiaqi Yan wrote: > Traversal on llist (e.g. llist_for_each_safe) is only safe AFTER entries > 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 (Sorry if stupid question...) folio_set_hugetlb_hwpoison() also calls llist_for_each_safe() but it still traverses the list without calling llist_del_all(). This convention applies only when removing item(s)? Thanks, Naoya Horiguchi > --- > mm/memory-failure.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > 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_head(struct folio *folio) > > static unsigned long __folio_free_raw_hwp(struct folio *folio, bool move_flag) > { > - struct llist_head *head; > - struct llist_node *t, *tnode; > + struct llist_node *t, *tnode, *head; > unsigned long count = 0; > > - head = raw_hwp_list_head(folio); > - llist_for_each_safe(tnode, t, head->first) { > + head = llist_del_all(raw_hwp_list_head(folio)); > + llist_for_each_safe(tnode, t, head) { > struct raw_hwp_page *p = 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 > > >