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Thu, 06 Jul 2023 11:25:26 -0700 (PDT) MIME-Version: 1.0 References: <20230623164015.3431990-1-jiaqiyan@google.com> <20230623164015.3431990-3-jiaqiyan@google.com> <20230705235705.GE41006@monkey> In-Reply-To: <20230705235705.GE41006@monkey> From: Jiaqi Yan Date: Thu, 6 Jul 2023 11:25:15 -0700 Message-ID: Subject: Re: [PATCH v2 2/4] mm/hwpoison: check if a subpage of a hugetlb folio is raw HWPOISON 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: rspam12 X-Rspamd-Queue-Id: DD4DEC0012 X-Stat-Signature: zxeqk6jzour6nig51drba1oof3mh7zyx X-HE-Tag: 1688667927-315347 X-HE-Meta: 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 O0rW1eSD r1nis2AXZ3rKvNhBl4/p9QxFvx9zyxXe0pY3h8hRGNiPpSk28fMfyzhGFBkf8dS3yB1ff1JTlgGwI8TLmWhtL819Bff+usjJCJ1CdmrnHFt4WmN8kOjtGdHoTN+xksQv2f8/Pqqs6oEIFfiynt/xY8BOMJBuqftI0yVcP+lf0kCZ7ZODhBDrqeGClIjtffo6d659Gi71b4K36Iiw9m/oIFsuAg93HPlZvYbEYVGAV6NQYKqpqA/UybVp9E3lBOD4A2kwZwq+At+TZKsljyzm8mzTTQg== 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 4:57=E2=80=AFPM Mike Kravetz wrote: > > On 06/23/23 16:40, Jiaqi Yan wrote: > > Adds the functionality to tell if a subpage of a hugetlb folio is a > > raw HWPOISON page. This functionality relies on RawHwpUnreliable to > > be not set; otherwise hugepage's HWPOISON list becomes meaningless. > > > > Exports this functionality to be immediately used in the read operation > > for hugetlbfs. > > > > Signed-off-by: Jiaqi Yan > > --- > > include/linux/hugetlb.h | 19 +++++++++++++++++++ > > include/linux/mm.h | 7 +++++++ > > mm/hugetlb.c | 10 ++++++++++ > > mm/memory-failure.c | 34 ++++++++++++++++++++++++---------- > > 4 files changed, 60 insertions(+), 10 deletions(-) > > > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > > index 21f942025fec..8b73a12b7b38 100644 > > --- a/include/linux/hugetlb.h > > +++ b/include/linux/hugetlb.h > > @@ -1013,6 +1013,25 @@ void hugetlb_register_node(struct node *node); > > void hugetlb_unregister_node(struct node *node); > > #endif > > > > +/* > > + * Struct raw_hwp_page represents information about "raw error page", > > + * constructing singly linked list from ->_hugetlb_hwpoison field of f= olio. > > + */ > > +struct raw_hwp_page { > > + struct llist_node node; > > + struct page *page; > > +}; > > + > > +static inline struct llist_head *raw_hwp_list_head(struct folio *folio= ) > > +{ > > + return (struct llist_head *)&folio->_hugetlb_hwpoison; > > +} > > + > > +/* > > + * Check if a given raw @subpage in a hugepage @folio is HWPOISON. > > + */ > > +bool is_raw_hwp_subpage(struct folio *folio, struct page *subpage); > > + > > #else /* CONFIG_HUGETLB_PAGE */ > > struct hstate {}; > > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index 66032f0d515c..41a283bd41a7 100644 > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -3671,6 +3671,7 @@ extern const struct attribute_group memory_failur= e_attr_group; > > extern void memory_failure_queue(unsigned long pfn, int flags); > > extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags, > > bool *migratable_cleared); > > +extern bool __is_raw_hwp_subpage(struct folio *folio, struct page *sub= page); > > void num_poisoned_pages_inc(unsigned long pfn); > > void num_poisoned_pages_sub(unsigned long pfn, long i); > > struct task_struct *task_early_kill(struct task_struct *tsk, int force= _early); > > @@ -3685,6 +3686,12 @@ static inline int __get_huge_page_for_hwpoison(u= nsigned long pfn, int flags, > > return 0; > > } > > > > +static inline bool __is_raw_hwp_subpage(struct folio *folio, > > + struct page *subpage) > > +{ > > + return false; > > +} > > + > > static inline void num_poisoned_pages_inc(unsigned long pfn) > > { > > } > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > > index ea24718db4af..6b860de87590 100644 > > --- a/mm/hugetlb.c > > +++ b/mm/hugetlb.c > > @@ -7377,6 +7377,16 @@ int get_huge_page_for_hwpoison(unsigned long pfn= , int flags, > > return ret; > > } > > > > +bool is_raw_hwp_subpage(struct folio *folio, struct page *subpage) > > +{ > > + bool ret; > > + > > + spin_lock_irq(&hugetlb_lock); > > + ret =3D __is_raw_hwp_subpage(folio, subpage); > > + spin_unlock_irq(&hugetlb_lock); > > Can you describe what races the hugetlb_lock prevents here? I think we should sync here with __get_huge_page_for_hwpoison, who iterates and inserts an entry to raw_hwp_list. llist itself doesn't ensure insertion is synchronized with iterating from __is_raw_hwp_subpage. > -- > Mike Kravetz > > > + return ret; > > +} > > + > > void folio_putback_active_hugetlb(struct folio *folio) > > { > > spin_lock_irq(&hugetlb_lock); > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > > index c415c3c462a3..891248e2930e 100644 > > --- a/mm/memory-failure.c > > +++ b/mm/memory-failure.c > > @@ -1809,18 +1809,32 @@ EXPORT_SYMBOL_GPL(mf_dax_kill_procs); > > #endif /* CONFIG_FS_DAX */ > > > > #ifdef CONFIG_HUGETLB_PAGE > > -/* > > - * Struct raw_hwp_page represents information about "raw error page", > > - * constructing singly linked list from ->_hugetlb_hwpoison field of f= olio. > > - */ > > -struct raw_hwp_page { > > - struct llist_node node; > > - struct page *page; > > -}; > > > > -static inline struct llist_head *raw_hwp_list_head(struct folio *folio= ) > > +bool __is_raw_hwp_subpage(struct folio *folio, struct page *subpage) > > { > > - return (struct llist_head *)&folio->_hugetlb_hwpoison; > > + struct llist_head *raw_hwp_head; > > + struct raw_hwp_page *p, *tmp; > > + bool ret =3D false; > > + > > + if (!folio_test_hwpoison(folio)) > > + return false; > > + > > + /* > > + * When RawHwpUnreliable is set, kernel lost track of which subpa= ges > > + * are HWPOISON. So return as if ALL subpages are HWPOISONed. > > + */ > > + if (folio_test_hugetlb_raw_hwp_unreliable(folio)) > > + return true; > > + > > + raw_hwp_head =3D raw_hwp_list_head(folio); > > + llist_for_each_entry_safe(p, tmp, raw_hwp_head->first, node) { > > + if (subpage =3D=3D p->page) { > > + ret =3D true; > > + break; > > + } > > + } > > + > > + return ret; > > } > > > > static unsigned long __folio_free_raw_hwp(struct folio *folio, bool mo= ve_flag) > > -- > > 2.41.0.162.gfafddb0af9-goog > >