| Message ID | 1581942239-112920-1-git-send-email-chengzhihao1@huawei.com |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [4.4] ubifs: Fix deadlock in concurrent bulk-read and writepage | expand |
On Mon, Feb 17, 2020 at 08:23:59PM +0800, Zhihao Cheng wrote: > [ Upstream commit f5de5b83303e61b1f3fb09bd77ce3ac2d7a475f2 ] > > In ubifs, concurrent execution of writepage and bulk read on the same file > may cause ABBA deadlock, for example (Reproduce method see Link): > > Process A(Bulk-read starts from page4) Process B(write page4 back) > vfs_read wb_workfn or fsync > ... ... > generic_file_buffered_read write_cache_pages > ubifs_readpage LOCK(page4) > > ubifs_bulk_read ubifs_writepage > LOCK(ui->ui_mutex) ubifs_write_inode > > ubifs_do_bulk_read LOCK(ui->ui_mutex) > find_or_create_page(alloc page4) ↑ > LOCK(page4) <-- ABBA deadlock occurs! > > In order to ensure the serialization execution of bulk read, we can't > remove the big lock 'ui->ui_mutex' in ubifs_bulk_read(). Instead, we > allow ubifs_do_bulk_read() to lock page failed by replacing > find_or_create_page(FGP_LOCK) with > pagecache_get_page(FGP_LOCK | FGP_NOWAIT). > > Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com> > Suggested-by: zhangyi (F) <yi.zhang@huawei.com> > Cc: <Stable@vger.kernel.org> > Fixes: 4793e7c5e1c ("UBIFS: add bulk-read facility") > Link: https://bugzilla.kernel.org/show_bug.cgi?id=206153 > Signed-off-by: Richard Weinberger <richard@nod.at> > --- > fs/ubifs/file.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c > index b895af7d8d80..e6d0a7df341d 100644 > --- a/fs/ubifs/file.c > +++ b/fs/ubifs/file.c > @@ -782,8 +782,9 @@ static int ubifs_do_bulk_read(struct ubifs_info *c, struct bu_info *bu, > > if (page_offset > end_index) > break; > - page = find_or_create_page(mapping, page_offset, > - GFP_NOFS | __GFP_COLD); > + page = pagecache_get_page(mapping, page_offset, > + FGP_LOCK|FGP_ACCESSED|FGP_CREAT|FGP_NOWAIT, > + GFP_NOFS | __GFP_COLD); > if (!page) > break; > if (!PageUptodate(page)) > -- > 2.7.4 > Now applied, thanks! greg k-h
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c index b895af7d8d80..e6d0a7df341d 100644 --- a/fs/ubifs/file.c +++ b/fs/ubifs/file.c @@ -782,8 +782,9 @@ static int ubifs_do_bulk_read(struct ubifs_info *c, struct bu_info *bu, if (page_offset > end_index) break; - page = find_or_create_page(mapping, page_offset, - GFP_NOFS | __GFP_COLD); + page = pagecache_get_page(mapping, page_offset, + FGP_LOCK|FGP_ACCESSED|FGP_CREAT|FGP_NOWAIT, + GFP_NOFS | __GFP_COLD); if (!page) break; if (!PageUptodate(page))
[ Upstream commit f5de5b83303e61b1f3fb09bd77ce3ac2d7a475f2 ] In ubifs, concurrent execution of writepage and bulk read on the same file may cause ABBA deadlock, for example (Reproduce method see Link): Process A(Bulk-read starts from page4) Process B(write page4 back) vfs_read wb_workfn or fsync ... ... generic_file_buffered_read write_cache_pages ubifs_readpage LOCK(page4) ubifs_bulk_read ubifs_writepage LOCK(ui->ui_mutex) ubifs_write_inode ubifs_do_bulk_read LOCK(ui->ui_mutex) find_or_create_page(alloc page4) ↑ LOCK(page4) <-- ABBA deadlock occurs! In order to ensure the serialization execution of bulk read, we can't remove the big lock 'ui->ui_mutex' in ubifs_bulk_read(). Instead, we allow ubifs_do_bulk_read() to lock page failed by replacing find_or_create_page(FGP_LOCK) with pagecache_get_page(FGP_LOCK | FGP_NOWAIT). Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com> Suggested-by: zhangyi (F) <yi.zhang@huawei.com> Cc: <Stable@vger.kernel.org> Fixes: 4793e7c5e1c ("UBIFS: add bulk-read facility") Link: https://bugzilla.kernel.org/show_bug.cgi?id=206153 Signed-off-by: Richard Weinberger <richard@nod.at> --- fs/ubifs/file.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)