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Tue, 26 Aug 2025 23:47:44 -0400 X-MC-Unique: 0IbwmORUNnmdlMb_tLuFXg-1 X-Mimecast-MFC-AGG-ID: 0IbwmORUNnmdlMb_tLuFXg_1756266462 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C6A331956095; Wed, 27 Aug 2025 03:47:41 +0000 (UTC) Received: from localhost (unknown [10.72.112.154]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5FED31955F24; Wed, 27 Aug 2025 03:47:38 +0000 (UTC) Date: Wed, 27 Aug 2025 11:47:34 +0800 From: Baoquan He To: Kairui Song Cc: linux-mm@kvack.org, Andrew Morton , Matthew Wilcox , Hugh Dickins , Chris Li , Barry Song , Nhat Pham , Kemeng Shi , Baolin Wang , Ying Huang , Johannes Weiner , David Hildenbrand , Yosry Ahmed , Lorenzo Stoakes , Zi Yan , linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/9] mm, swap: tidy up swap device and cluster info helpers Message-ID: References: <20250822192023.13477-1-ryncsn@gmail.com> <20250822192023.13477-5-ryncsn@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250822192023.13477-5-ryncsn@gmail.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: C761B80005 X-Stat-Signature: uu8ofzetjwc1smkyd6iqp4h1w3xca3mr X-HE-Tag: 1756266468-197846 X-HE-Meta: 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 zQxPAyow ddyUxGA++2Dis+Cssnnke0zSnbiJpFjbi+Cf4OalwSluuXszHYb1EPfCyjLjTJKhPE1Px5wc0eAdJ+bqBolAk+lo+3Pe+WnlhxQPkWbkUaimOuu50Rt7ENXy2Sqn+P27qwrJrAywUYPqQ4mJp/np9BmfWHCHX220fkOiNOQh5FYpYjhNOQ6p0zenbYVvk92xEEW6APOJZjQ7ARcM8AvsckiXIokXUAD+6AxHCV/XC/1UPEqbEPebYVCE6xDQ5KMT9D9kIjRqetgmbB/T1GFtAal7zSNaM5P80808jBZsjLOJg4RoWxvhnwQKY25hVD2VMCmxiZJF/rpFA5Mqa8JJDFx+JW9NvA+ZT2H8snYG/Bdni7YOInp4AoicGlfEAwdfa0IAp1E81dWc7RBsOZUk9GqL9Qw== 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 08/23/25 at 03:20am, Kairui Song wrote: ...... > diff --git a/mm/swap.h b/mm/swap.h > index 223b40f2d37e..7b3efaa51624 100644 > --- a/mm/swap.h > +++ b/mm/swap.h > @@ -15,6 +15,8 @@ extern int page_cluster; > #define swap_entry_order(order) 0 > #endif > > +extern struct swap_info_struct *swap_info[]; > + > /* > * We use this to track usage of a cluster. A cluster is a block of swap disk > * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All > @@ -53,9 +55,28 @@ enum swap_cluster_flags { > #include /* for swp_offset */ > #include /* for bio_end_io_t */ > > +/* > + * Callers of all swp_* helpers here must ensure the entry is valid, and > + * pin the swap device by reference or in other ways. > + */ > +static inline struct swap_info_struct *swp_type_info(int type) > +{ > + struct swap_info_struct *si; > + > + si = READ_ONCE(swap_info[type]); /* rcu_dereference() */ > + VM_WARN_ON_ONCE(percpu_ref_is_zero(&si->users)); /* race with swapoff */ > + return si; > +} > + > +static inline struct swap_info_struct *swp_info(swp_entry_t entry) > +{ > + return swp_type_info(swp_type(entry)); > +} swp_type_info() is only used by swp_info() in the whole series, can we open code it in swp_info()? If you plan to use it in later phase of swap table patchset, then please ignore this. > + > static inline struct swap_cluster_info *swp_offset_cluster( > struct swap_info_struct *si, pgoff_t offset) > { > + VM_WARN_ON_ONCE(percpu_ref_is_zero(&si->users)); /* race with swapoff */ > return &si->cluster_info[offset / SWAPFILE_CLUSTER]; > } > > @@ -65,6 +86,7 @@ static inline struct swap_cluster_info *swap_cluster_lock( > { > struct swap_cluster_info *ci = swp_offset_cluster(si, offset); > > + VM_WARN_ON_ONCE(percpu_ref_is_zero(&si->users)); /* race with swapoff */ > spin_lock(&ci->lock); > return ci; > } > @@ -164,7 +186,7 @@ void swap_update_readahead(struct folio *folio, struct vm_area_struct *vma, > > static inline unsigned int folio_swap_flags(struct folio *folio) > { > - return swp_swap_info(folio->swap)->flags; > + return swp_info(folio->swap)->flags; > } > > /* > @@ -175,7 +197,7 @@ static inline unsigned int folio_swap_flags(struct folio *folio) > static inline int swap_zeromap_batch(swp_entry_t entry, int max_nr, > bool *is_zeromap) > { > - struct swap_info_struct *sis = swp_swap_info(entry); > + struct swap_info_struct *sis = swp_info(entry); > unsigned long start = swp_offset(entry); > unsigned long end = start + max_nr; > bool first_bit; > @@ -194,7 +216,7 @@ static inline int swap_zeromap_batch(swp_entry_t entry, int max_nr, > > static inline int non_swapcache_batch(swp_entry_t entry, int max_nr) > { > - struct swap_info_struct *si = swp_swap_info(entry); > + struct swap_info_struct *si = swp_info(entry); > pgoff_t offset = swp_offset(entry); > int i; > > @@ -213,6 +235,11 @@ static inline int non_swapcache_batch(swp_entry_t entry, int max_nr) > > #else /* CONFIG_SWAP */ > struct swap_iocb; > +static inline struct swap_info_struct *swp_info(swp_entry_t entry) > +{ > + return NULL; > +} > + > static inline void swap_read_folio(struct folio *folio, struct swap_iocb **plug) > { > } ......