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bh=GVXJ9CoqQx/pIpf3FQPir+UyUtnBDDswwBlUb1tywgg=; b=itCQ22TsKCGEi7SS+DASJiYifq igeU+PIWCAXoCeY9aQW7mYN6rQR/F3VX+s8opkz6QsiBHgVv6RCU0yfgomgAxXRFqWfsUxml63U1e /yPtClKJxj3hSw3An4t7+YmuqoQetQ9hZw0DNYF7r0HCkG7zczHgGIff4ho5yjhQAE9dxN7jE/Xb8 aOw9W4LEBIG/NVFL3ocpEkooBeLXfrtQJNLaFIuBlvWjlKsxDYcYk2L3su6bdaSx8Wr+k4/e79dLH //BCfezd5Gnxy6Ivcmd0q0Wmo8OHGop0Fky5PGKXe53HV6w4RWeZio6uabS4ebpCbXCEyt/3nPra9 16L1QOYA==; Received: from willy by casper.infradead.org with local (Exim 4.98.1 #2 (Red Hat Linux)) id 1tzzZX-00000009gsm-3XPn; Wed, 02 Apr 2025 15:00:07 +0000 From: "Matthew Wilcox (Oracle)" To: linux-fsdevel@vger.kernel.org Cc: "Matthew Wilcox (Oracle)" , intel-gfx@lists.freedesktop.org, linux-mm@kvack.org, dri-devel@lists.freedesktop.org, Baolin Wang Subject: [PATCH v2 8/9] mm: Remove swap_writepage() and shmem_writepage() Date: Wed, 2 Apr 2025 16:00:02 +0100 Message-ID: <20250402150005.2309458-9-willy@infradead.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250402150005.2309458-1-willy@infradead.org> References: <20250402150005.2309458-1-willy@infradead.org> MIME-Version: 1.0 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: AC65B1C0013 X-Stat-Signature: wcbqb7dur5ue3py3qgh4rczibzsi38hm X-Rspam-User: X-HE-Tag: 1743606011-907775 X-HE-Meta: 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 bD69z3mE E5+B1m+CqqiC7aU7a8EWHnXf0f+Ytb/QaUu41EgCZY/pR/qW63ct6/xp0vbC9EHyULqPMIdTyrrKa8lJMHAkDeOBlo0nejwbn5abmi9+cHk47sbGp/Fw/CIWm8jXpdblgKgTUX3v2gk3LzvUX7mCNLa0hq2lv2r7xrO9925M8B83fIKAGsSdkiu1NwiiliehNhYMAIg1Y3J94vsptMLotxIa5T2IaCeBDTDNwdxMgWmEbh9gqRTKEjVZf68K9P9l49EbnM7wgLT0T+mKPE1bBiwmb3pLNfQzyWA38OYM7++fz8jwtXMHvATDCYg== 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: Call swap_writeout() and shmem_writeout() from pageout() instead. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Baolin Wang Tested-by: Baolin Wang --- block/blk-wbt.c | 2 +- mm/page_io.c | 3 +-- mm/shmem.c | 23 +++++------------------ mm/swap.h | 4 ++-- mm/swap_state.c | 1 - mm/swapfile.c | 2 +- mm/vmscan.c | 28 ++++++++++++++++------------ 7 files changed, 26 insertions(+), 37 deletions(-) diff --git a/block/blk-wbt.c b/block/blk-wbt.c index f1754d07f7e0..60885731e8ab 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -37,7 +37,7 @@ enum wbt_flags { WBT_TRACKED = 1, /* write, tracked for throttling */ WBT_READ = 2, /* read */ - WBT_SWAP = 4, /* write, from swap_writepage() */ + WBT_SWAP = 4, /* write, from swap_writeout() */ WBT_DISCARD = 8, /* discard */ WBT_NR_BITS = 4, /* number of bits */ diff --git a/mm/page_io.c b/mm/page_io.c index 4bce19df557b..f7716b6569fa 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -237,9 +237,8 @@ static void swap_zeromap_folio_clear(struct folio *folio) * We may have stale swap cache pages in memory: notice * them here and get rid of the unnecessary final write. */ -int swap_writepage(struct page *page, struct writeback_control *wbc) +int swap_writeout(struct folio *folio, struct writeback_control *wbc) { - struct folio *folio = page_folio(page); int ret; if (folio_free_swap(folio)) { diff --git a/mm/shmem.c b/mm/shmem.c index 7d377ceae035..858cee02ca49 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -98,7 +98,7 @@ static struct vfsmount *shm_mnt __ro_after_init; #define SHORT_SYMLINK_LEN 128 /* - * shmem_fallocate communicates with shmem_fault or shmem_writepage via + * shmem_fallocate communicates with shmem_fault or shmem_writeout via * inode->i_private (with i_rwsem making sure that it has only one user at * a time): we would prefer not to enlarge the shmem inode just for that. */ @@ -107,7 +107,7 @@ struct shmem_falloc { pgoff_t start; /* start of range currently being fallocated */ pgoff_t next; /* the next page offset to be fallocated */ pgoff_t nr_falloced; /* how many new pages have been fallocated */ - pgoff_t nr_unswapped; /* how often writepage refused to swap out */ + pgoff_t nr_unswapped; /* how often writeout refused to swap out */ }; struct shmem_options { @@ -446,7 +446,7 @@ static void shmem_recalc_inode(struct inode *inode, long alloced, long swapped) /* * Special case: whereas normally shmem_recalc_inode() is called * after i_mapping->nrpages has already been adjusted (up or down), - * shmem_writepage() has to raise swapped before nrpages is lowered - + * shmem_writeout() has to raise swapped before nrpages is lowered - * to stop a racing shmem_recalc_inode() from thinking that a page has * been freed. Compensate here, to avoid the need for a followup call. */ @@ -1536,11 +1536,6 @@ int shmem_unuse(unsigned int type) return error; } -static int shmem_writepage(struct page *page, struct writeback_control *wbc) -{ - return shmem_writeout(page_folio(page), wbc); -} - /** * shmem_writeout - Write the folio to swap * @folio: The folio to write @@ -1558,13 +1553,6 @@ int shmem_writeout(struct folio *folio, struct writeback_control *wbc) int nr_pages; bool split = false; - /* - * Our capabilities prevent regular writeback or sync from ever calling - * shmem_writepage; but a stacking filesystem might use ->writepage of - * its underlying filesystem, in which case tmpfs should write out to - * swap only in response to memory pressure, and not for the writeback - * threads or sync. - */ if (WARN_ON_ONCE(!wbc->for_reclaim)) goto redirty; @@ -1653,7 +1641,7 @@ int shmem_writeout(struct folio *folio, struct writeback_control *wbc) mutex_unlock(&shmem_swaplist_mutex); BUG_ON(folio_mapped(folio)); - return swap_writepage(&folio->page, wbc); + return swap_writeout(folio, wbc); } list_del_init(&info->swaplist); @@ -3776,7 +3764,7 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset, index--; /* - * Inform shmem_writepage() how far we have reached. + * Inform shmem_writeout() how far we have reached. * No need for lock or barrier: we have the page lock. */ if (!folio_test_uptodate(folio)) @@ -5199,7 +5187,6 @@ static int shmem_error_remove_folio(struct address_space *mapping, } static const struct address_space_operations shmem_aops = { - .writepage = shmem_writepage, .dirty_folio = noop_dirty_folio, #ifdef CONFIG_TMPFS .write_begin = shmem_write_begin, diff --git a/mm/swap.h b/mm/swap.h index 6f4a3f927edb..aa62463976d5 100644 --- a/mm/swap.h +++ b/mm/swap.h @@ -20,7 +20,7 @@ static inline void swap_read_unplug(struct swap_iocb *plug) __swap_read_unplug(plug); } void swap_write_unplug(struct swap_iocb *sio); -int swap_writepage(struct page *page, struct writeback_control *wbc); +int swap_writeout(struct folio *folio, struct writeback_control *wbc); void __swap_writepage(struct folio *folio, struct writeback_control *wbc); /* linux/mm/swap_state.c */ @@ -141,7 +141,7 @@ static inline struct folio *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, return NULL; } -static inline int swap_writepage(struct page *p, struct writeback_control *wbc) +static inline int swap_writeout(struct folio *f, struct writeback_control *wbc) { return 0; } diff --git a/mm/swap_state.c b/mm/swap_state.c index 68fd981b514f..ec2b1c9c9926 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -30,7 +30,6 @@ * vmscan's shrink_folio_list. */ static const struct address_space_operations swap_aops = { - .writepage = swap_writepage, .dirty_folio = noop_dirty_folio, #ifdef CONFIG_MIGRATION .migrate_folio = migrate_folio, diff --git a/mm/swapfile.c b/mm/swapfile.c index 2eff8b51a945..f9fa30ae13be 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2359,7 +2359,7 @@ static int try_to_unuse(unsigned int type) * Limit the number of retries? No: when mmget_not_zero() * above fails, that mm is likely to be freeing swap from * exit_mmap(), which proceeds at its own independent pace; - * and even shmem_writepage() could have been preempted after + * and even shmem_writeout() could have been preempted after * folio_alloc_swap(), temporarily hiding that swap. It's easy * and robust (though cpu-intensive) just to keep retrying. */ diff --git a/mm/vmscan.c b/mm/vmscan.c index b620d74b0f66..d172c998d592 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -653,16 +653,16 @@ typedef enum { static pageout_t pageout(struct folio *folio, struct address_space *mapping, struct swap_iocb **plug, struct list_head *folio_list) { + int (*writeout)(struct folio *, struct writeback_control *); + /* - * If the folio is dirty, only perform writeback if that write - * will be non-blocking. To prevent this allocation from being - * stalled by pagecache activity. But note that there may be - * stalls if we need to run get_block(). We could test - * PagePrivate for that. - * - * If this process is currently in __generic_file_write_iter() against - * this folio's queue, we can perform writeback even if that - * will block. + * We no longer attempt to writeback filesystem folios here, other + * than tmpfs/shmem. That's taken care of in page-writeback. + * If we find a dirty filesystem folio at the end of the LRU list, + * typically that means the filesystem is saturating the storage + * with contiguous writes and telling it to write a folio here + * would only make the situation worse by injecting an element + * of random access. * * If the folio is swapcache, write it back even if that would * block, for some throttling. This happens by accident, because @@ -685,7 +685,11 @@ static pageout_t pageout(struct folio *folio, struct address_space *mapping, } return PAGE_KEEP; } - if (mapping->a_ops->writepage == NULL) + if (shmem_mapping(mapping)) + writeout = shmem_writeout; + else if (folio_test_anon(folio)) + writeout = swap_writeout; + else return PAGE_ACTIVATE; if (folio_clear_dirty_for_io(folio)) { @@ -708,7 +712,7 @@ static pageout_t pageout(struct folio *folio, struct address_space *mapping, wbc.list = folio_list; folio_set_reclaim(folio); - res = mapping->a_ops->writepage(&folio->page, &wbc); + res = writeout(folio, &wbc); if (res < 0) handle_write_error(mapping, folio, res); if (res == AOP_WRITEPAGE_ACTIVATE) { @@ -717,7 +721,7 @@ static pageout_t pageout(struct folio *folio, struct address_space *mapping, } if (!folio_test_writeback(folio)) { - /* synchronous write or broken a_ops? */ + /* synchronous write? */ folio_clear_reclaim(folio); } trace_mm_vmscan_write_folio(folio);