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Date: Tue, 5 Mar 2019 19:46:54 -0800 From: Jaegeuk Kim <jaegeuk@...nel.org> To: Chao Yu <yuchao0@...wei.com> Cc: linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org, chao@...nel.org Subject: Re: [PATCH 1/2] f2fs: fix to add refcount once page is tagged PG_private On 03/05, Chao Yu wrote: > As Gao Xiang reported in bugzilla: > > https://bugzilla.kernel.org/show_bug.cgi?id=202749 > > f2fs may skip pageout() due to incorrect page reference count. > > The problem here is that MM defined the rule [1] very clearly that > once page was set with PG_private flag, we should increment the > refcount in that page, also main flows like pageout(), migrate_page() > will assume there is one additional page reference count if > page_has_private() returns true. > > But currently, f2fs won't add/del refcount when changing PG_private > flag. Anyway, f2fs should follow MM's rule to make MM's related flows > running as expected. > > [1] https://lore.kernel.org/lkml/2b19b3c4-2bc4-15fa-15cc-27a13e5c7af1@aol.com/ > > Reported-by: Gao Xiang <gaoxiang25@...wei.com> > Signed-off-by: Chao Yu <yuchao0@...wei.com> > --- > fs/f2fs/checkpoint.c | 11 +++++++++-- > fs/f2fs/data.c | 32 ++++++++++++++++++++------------ > fs/f2fs/dir.c | 6 +++++- > fs/f2fs/node.c | 6 +++++- > fs/f2fs/segment.c | 23 +++++++++++++++++------ > 5 files changed, 56 insertions(+), 22 deletions(-) > > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c > index c65a1e8e1e95..4e0e93af5ce0 100644 > --- a/fs/f2fs/checkpoint.c > +++ b/fs/f2fs/checkpoint.c > @@ -406,7 +406,11 @@ static int f2fs_set_meta_page_dirty(struct page *page) > if (!PageDirty(page)) { > __set_page_dirty_nobuffers(page); > inc_page_count(F2FS_P_SB(page), F2FS_DIRTY_META); > - SetPagePrivate(page); > + > + if (!PagePrivate(page)) { > + get_page(page); > + SetPagePrivate(page); Can we add generic functions? f2fs_set_page_private(page) { if (PagePrivate(page)) return; SetPagePrivate(page); get_page(page); } f2fs_clear_page_private(page) { if (!PagePrivate(page)) return; set_page_private(page, 0); ClearPagePrivate(page); f2fs_put_page(page, 0); } > > + } > f2fs_trace_pid(page); > return 1; > } > @@ -957,7 +961,10 @@ void f2fs_update_dirty_page(struct inode *inode, struct page *page) > inode_inc_dirty_pages(inode); > spin_unlock(&sbi->inode_lock[type]); > > - SetPagePrivate(page); > + if (!PagePrivate(page)) { > + get_page(page); > + SetPagePrivate(page); > + } > f2fs_trace_pid(page); > } > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > index 3f3becd46362..46924d4f69d0 100644 > --- a/fs/f2fs/data.c > +++ b/fs/f2fs/data.c > @@ -2715,8 +2715,11 @@ void f2fs_invalidate_page(struct page *page, unsigned int offset, > if (IS_ATOMIC_WRITTEN_PAGE(page)) > return f2fs_drop_inmem_page(inode, page); > > - set_page_private(page, 0); > - ClearPagePrivate(page); > + if (PagePrivate(page)) { > + set_page_private(page, 0); > + ClearPagePrivate(page); > + f2fs_put_page(page, 0); > + } > } > > int f2fs_release_page(struct page *page, gfp_t wait) > @@ -2730,8 +2733,11 @@ int f2fs_release_page(struct page *page, gfp_t wait) > return 0; > > clear_cold_data(page); > - set_page_private(page, 0); > - ClearPagePrivate(page); > + if (PagePrivate(page)) { > + set_page_private(page, 0); > + ClearPagePrivate(page); > + f2fs_put_page(page, 0); > + } > return 1; > } > > @@ -2799,12 +2805,8 @@ int f2fs_migrate_page(struct address_space *mapping, > return -EAGAIN; > } > > - /* > - * A reference is expected if PagePrivate set when move mapping, > - * however F2FS breaks this for maintaining dirty page counts when > - * truncating pages. So here adjusting the 'extra_count' make it work. > - */ > - extra_count = (atomic_written ? 1 : 0) - page_has_private(page); > + /* one extra reference was held for atomic_write page */ > + extra_count = atomic_written ? 1 : 0; > rc = migrate_page_move_mapping(mapping, newpage, > page, mode, extra_count); > if (rc != MIGRATEPAGE_SUCCESS) { > @@ -2825,9 +2827,15 @@ int f2fs_migrate_page(struct address_space *mapping, > get_page(newpage); > } > > - if (PagePrivate(page)) > + if (PagePrivate(page)) { > + get_page(newpage); > SetPagePrivate(newpage); > - set_page_private(newpage, page_private(page)); > + set_page_private(newpage, page_private(page)); > + > + set_page_private(page, 0); > + ClearPagePrivate(page); > + f2fs_put_page(page, 0); > + } > > if (mode != MIGRATE_SYNC_NO_COPY) > migrate_page_copy(newpage, page); > diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c > index 103f3686a045..fbbafb04a431 100644 > --- a/fs/f2fs/dir.c > +++ b/fs/f2fs/dir.c > @@ -728,7 +728,11 @@ void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct page *page, > !f2fs_truncate_hole(dir, page->index, page->index + 1)) { > f2fs_clear_page_cache_dirty_tag(page); > clear_page_dirty_for_io(page); > - ClearPagePrivate(page); > + if (PagePrivate(page)) { > + set_page_private(page, 0); > + ClearPagePrivate(page); > + f2fs_put_page(page, 0); > + } > ClearPageUptodate(page); > clear_cold_data(page); > inode_dec_dirty_pages(dir); > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c > index f6ff84e29749..ce97a9885105 100644 > --- a/fs/f2fs/node.c > +++ b/fs/f2fs/node.c > @@ -1961,7 +1961,11 @@ static int f2fs_set_node_page_dirty(struct page *page) > if (!PageDirty(page)) { > __set_page_dirty_nobuffers(page); > inc_page_count(F2FS_P_SB(page), F2FS_DIRTY_NODES); > - SetPagePrivate(page); > + > + if (!PagePrivate(page)) { > + get_page(page); > + SetPagePrivate(page); > + } > f2fs_trace_pid(page); > return 1; > } > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index e730c334abba..2d77dd133a4e 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -191,8 +191,11 @@ void f2fs_register_inmem_page(struct inode *inode, struct page *page) > > f2fs_trace_pid(page); > > - set_page_private(page, (unsigned long)ATOMIC_WRITTEN_PAGE); > - SetPagePrivate(page); > + if (!PagePrivate(page)) { > + get_page(page); > + SetPagePrivate(page); > + set_page_private(page, (unsigned long)ATOMIC_WRITTEN_PAGE); > + } > > new = f2fs_kmem_cache_alloc(inmem_entry_slab, GFP_NOFS); > > @@ -280,8 +283,11 @@ static int __revoke_inmem_pages(struct inode *inode, > ClearPageUptodate(page); > clear_cold_data(page); > } > - set_page_private(page, 0); > - ClearPagePrivate(page); > + if (PagePrivate(page)) { > + set_page_private(page, 0); > + ClearPagePrivate(page); > + f2fs_put_page(page, 0); > + } > f2fs_put_page(page, 1); > > list_del(&cur->list); > @@ -370,8 +376,13 @@ void f2fs_drop_inmem_page(struct inode *inode, struct page *page) > kmem_cache_free(inmem_entry_slab, cur); > > ClearPageUptodate(page); > - set_page_private(page, 0); > - ClearPagePrivate(page); > + > + if (PagePrivate(page)) { > + set_page_private(page, 0); > + ClearPagePrivate(page); > + f2fs_put_page(page, 0); > + } > + > f2fs_put_page(page, 0); > > trace_f2fs_commit_inmem_page(page, INMEM_INVALIDATE); > -- > 2.18.0.rc1
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