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X-CSE-ConnectionGUID: lnKzB8XARPab7aFEfWXknA== X-CSE-MsgGUID: 3Cl6DiV3QW2sLilMqfll7A== X-IronPort-AV: E=McAfee;i="6600,9927,11095"; a="14263400" X-IronPort-AV: E=Sophos;i="6.08,219,1712646000"; d="scan'208";a="14263400" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jun 2024 18:48:56 -0700 X-CSE-ConnectionGUID: AJDDoL3CSsmiLqmGJ3s57g== X-CSE-MsgGUID: i2QhtHPaR5Cxya9kThcn2w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,219,1712646000"; d="scan'208";a="38735158" Received: from unknown (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jun 2024 18:48:55 -0700 From: "Huang, Ying" To: Yosry Ahmed Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: swap: remove 'synchronous' argument to swap_read_folio() In-Reply-To: <20240606210840.1650341-1-yosryahmed@google.com> (Yosry Ahmed's message of "Thu, 6 Jun 2024 21:08:40 +0000") References: <20240606210840.1650341-1-yosryahmed@google.com> Date: Fri, 07 Jun 2024 09:47:03 +0800 Message-ID: <871q598qy0.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A55FF14001A X-Stat-Signature: dqgzma5z6hrgpe43fn9hh7h5jiafhkhe X-HE-Tag: 1717724937-104811 X-HE-Meta: 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 1eK1tNWz 5NOqr5bEt3FKS0K0o8uHkO7o0FKcht2rUMRZ8gRWgJIPvBckOlbP/WaVHZa2LPHlsRu40fFOsPSnK2EVWUPB/KrFQDUiCWNTVbDMIMQukLLrEQnhN9Mmelm+GMwVLdk+OnaVrfhpPnB/CXcayHpyj+FDF08PuMpq+j8LRtD0hyADcegpsV/44F9oDwIfCLr3reciDSl6+9ynattXG1EVGtYznpyO6+SGAvIkbjLLYEMb65xw= 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: Yosry Ahmed writes: > swap_read_folio() reads the folio synchronously if synchronous is passed > as true or if SWP_SYNCHRONOUS_IO is set in swap_info_struct. The only > caller that passes synchronous=true is in do_swap_page() in the > SWP_SYNCHRONOUS_IO case. > > Hence, the argument is redundant, it is only set to true when the swap > read would have been synchronous anyway. Remove it. > > Signed-off-by: Yosry Ahmed LGTM, Thanks! Reviewed-by: "Huang, Ying" And, there's some history information in commit b243dcbf2f13 ("swap: remove remnants of polling from read_swap_cache_async"). " Commit [1] introduced IO polling support duding swapin to reduce swap read latency for block devices that can be polled. However later commit [2] removed polling support. Therefore it seems safe to remove do_poll parameter in read_swap_cache_async and always call swap_readpage with synchronous=false waiting for IO completion in folio_lock_or_retry. [1] commit 23955622ff8d ("swap: add block io poll in swapin path") [2] commit 9650b453a3d4 ("block: ignore RWF_HIPRI hint for sync dio") " IMO, it will help people to understand the code change to add some history information as above, or refer to the commit. -- Best Regards, Huang, Ying > --- > mm/memory.c | 2 +- > mm/page_io.c | 6 +++--- > mm/swap.h | 6 ++---- > mm/swap_state.c | 10 +++++----- > 4 files changed, 11 insertions(+), 13 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index db91304882312..2b3ef08e8bb7d 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -4113,7 +4113,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > > /* To provide entry to swap_read_folio() */ > folio->swap = entry; > - swap_read_folio(folio, true, NULL); > + swap_read_folio(folio, NULL); > folio->private = NULL; > } > } else { > diff --git a/mm/page_io.c b/mm/page_io.c > index 41e8d738c6d28..f1a9cfab6e748 100644 > --- a/mm/page_io.c > +++ b/mm/page_io.c > @@ -493,10 +493,10 @@ static void swap_read_folio_bdev_async(struct folio *folio, > submit_bio(bio); > } > > -void swap_read_folio(struct folio *folio, bool synchronous, > - struct swap_iocb **plug) > +void swap_read_folio(struct folio *folio, struct swap_iocb **plug) > { > struct swap_info_struct *sis = swp_swap_info(folio->swap); > + bool synchronous = sis->flags & SWP_SYNCHRONOUS_IO; > bool workingset = folio_test_workingset(folio); > unsigned long pflags; > bool in_thrashing; > @@ -521,7 +521,7 @@ void swap_read_folio(struct folio *folio, bool synchronous, > folio_unlock(folio); > } else if (data_race(sis->flags & SWP_FS_OPS)) { > swap_read_folio_fs(folio, plug); > - } else if (synchronous || (sis->flags & SWP_SYNCHRONOUS_IO)) { > + } else if (synchronous) { > swap_read_folio_bdev_sync(folio, sis); > } else { > swap_read_folio_bdev_async(folio, sis); > diff --git a/mm/swap.h b/mm/swap.h > index 2c0e96272d498..baa1fa946b347 100644 > --- a/mm/swap.h > +++ b/mm/swap.h > @@ -11,8 +11,7 @@ struct mempolicy; > /* linux/mm/page_io.c */ > int sio_pool_init(void); > struct swap_iocb; > -void swap_read_folio(struct folio *folio, bool do_poll, > - struct swap_iocb **plug); > +void swap_read_folio(struct folio *folio, struct swap_iocb **plug); > void __swap_read_unplug(struct swap_iocb *plug); > static inline void swap_read_unplug(struct swap_iocb *plug) > { > @@ -83,8 +82,7 @@ static inline unsigned int folio_swap_flags(struct folio *folio) > } > #else /* CONFIG_SWAP */ > struct swap_iocb; > -static inline void swap_read_folio(struct folio *folio, bool do_poll, > - struct swap_iocb **plug) > +static inline void swap_read_folio(struct folio *folio, struct swap_iocb **plug) > { > } > static inline void swap_write_unplug(struct swap_iocb *sio) > diff --git a/mm/swap_state.c b/mm/swap_state.c > index 0803eedeabe3d..994723cef8217 100644 > --- a/mm/swap_state.c > +++ b/mm/swap_state.c > @@ -567,7 +567,7 @@ struct folio *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, > mpol_cond_put(mpol); > > if (page_allocated) > - swap_read_folio(folio, false, plug); > + swap_read_folio(folio, plug); > return folio; > } > > @@ -684,7 +684,7 @@ struct folio *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask, > if (!folio) > continue; > if (page_allocated) { > - swap_read_folio(folio, false, &splug); > + swap_read_folio(folio, &splug); > if (offset != entry_offset) { > folio_set_readahead(folio); > count_vm_event(SWAP_RA); > @@ -701,7 +701,7 @@ struct folio *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask, > &page_allocated, false); > if (unlikely(page_allocated)) { > zswap_folio_swapin(folio); > - swap_read_folio(folio, false, NULL); > + swap_read_folio(folio, NULL); > } > return folio; > } > @@ -834,7 +834,7 @@ static struct folio *swap_vma_readahead(swp_entry_t targ_entry, gfp_t gfp_mask, > if (!folio) > continue; > if (page_allocated) { > - swap_read_folio(folio, false, &splug); > + swap_read_folio(folio, &splug); > if (addr != vmf->address) { > folio_set_readahead(folio); > count_vm_event(SWAP_RA); > @@ -853,7 +853,7 @@ static struct folio *swap_vma_readahead(swp_entry_t targ_entry, gfp_t gfp_mask, > &page_allocated, false); > if (unlikely(page_allocated)) { > zswap_folio_swapin(folio); > - swap_read_folio(folio, false, NULL); > + swap_read_folio(folio, NULL); > } > return folio; > }