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SubjectRe: [f2fs-dev] [PATCH] f2fs: fix livelock in swapfile writes
On 08/01, Chao Yu wrote:
> On 2019/8/1 4:43, Jaegeuk Kim wrote:
> > This patch fixes livelock in the below call path when writing swap pages.
> >
> > [46374.617256] c2 701 __switch_to+0xe4/0x100
> > [46374.617265] c2 701 __schedule+0x80c/0xbc4
> > [46374.617273] c2 701 schedule+0x74/0x98
> > [46374.617281] c2 701 rwsem_down_read_failed+0x190/0x234
> > [46374.617291] c2 701 down_read+0x58/0x5c
> > [46374.617300] c2 701 f2fs_map_blocks+0x138/0x9a8
> > [46374.617310] c2 701 get_data_block_dio_write+0x74/0x104
> > [46374.617320] c2 701 __blockdev_direct_IO+0x1350/0x3930
> > [46374.617331] c2 701 f2fs_direct_IO+0x55c/0x8bc
> > [46374.617341] c2 701 __swap_writepage+0x1d0/0x3e8
> > [46374.617351] c2 701 swap_writepage+0x44/0x54
> > [46374.617360] c2 701 shrink_page_list+0x140/0xe80
> > [46374.617371] c2 701 shrink_inactive_list+0x510/0x918
> > [46374.617381] c2 701 shrink_node_memcg+0x2d4/0x804
> > [46374.617391] c2 701 shrink_node+0x10c/0x2f8
> > [46374.617400] c2 701 do_try_to_free_pages+0x178/0x38c
> > [46374.617410] c2 701 try_to_free_pages+0x348/0x4b8
> > [46374.617419] c2 701 __alloc_pages_nodemask+0x7f8/0x1014
> > [46374.617429] c2 701 pagecache_get_page+0x184/0x2cc
> > [46374.617438] c2 701 f2fs_new_node_page+0x60/0x41c
> > [46374.617449] c2 701 f2fs_new_inode_page+0x50/0x7c
> > [46374.617460] c2 701 f2fs_init_inode_metadata+0x128/0x530
> > [46374.617472] c2 701 f2fs_add_inline_entry+0x138/0xd64
> > [46374.617480] c2 701 f2fs_do_add_link+0xf4/0x178
> > [46374.617488] c2 701 f2fs_create+0x1e4/0x3ac
> > [46374.617497] c2 701 path_openat+0xdc0/0x1308
> > [46374.617507] c2 701 do_filp_open+0x78/0x124
> > [46374.617516] c2 701 do_sys_open+0x134/0x248
> > [46374.617525] c2 701 SyS_openat+0x14/0x20
> >
> > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> > ---
> > fs/f2fs/data.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index abbf14e9bd72..f49f243fd54f 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -1372,7 +1372,7 @@ static int get_data_block_dio_write(struct inode *inode, sector_t iblock,
> > return __get_data_block(inode, iblock, bh_result, create,
> > F2FS_GET_BLOCK_DIO, NULL,
> > f2fs_rw_hint_to_seg_type(inode->i_write_hint),
> > - true);
> > + IS_SWAPFILE(inode) ? false : true);
>
> I suspect that we should use node_change for swapfile rather than just changing
> may_write field to skip lock.

Swap write should not change the node page.

>
> __do_map_lock()
> if (flag == F2FS_GET_BLOCK_PRE_AIO || IS_SWAPFILE(inode)) {
> ...
> } else {
> ...
> }
>
> Thanks,
>
>
> > }
> >
> > static int get_data_block_dio(struct inode *inode, sector_t iblock,
> >

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