* [f2fs-dev] [PATCH -next] f2fs: fix wrong dirty page count when race between mmap and fallocate.
@ 2022-08-15 8:15 Shuqi Zhang via Linux-f2fs-devel
2022-08-20 6:35 ` Chao Yu
0 siblings, 1 reply; 6+ messages in thread
From: Shuqi Zhang via Linux-f2fs-devel @ 2022-08-15 8:15 UTC (permalink / raw)
To: jaegeuk, chao; +Cc: zhangshuqi3, linux-kernel, linux-f2fs-devel
This is a BUG_ON issue as follows when running xfstest-generic-503:
WARNING: CPU: 21 PID: 1385 at fs/f2fs/inode.c:762 f2fs_evict_inode+0x847/0xaa0
Modules linked in:
CPU: 21 PID: 1385 Comm: umount Not tainted 5.19.0-rc5+ #73
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/01/2014
Call Trace:
evict+0x129/0x2d0
dispose_list+0x4f/0xb0
evict_inodes+0x204/0x230
generic_shutdown_super+0x5b/0x1e0
kill_block_super+0x29/0x80
kill_f2fs_super+0xe6/0x140
deactivate_locked_super+0x44/0xc0
deactivate_super+0x79/0x90
cleanup_mnt+0x114/0x1a0
__cleanup_mnt+0x16/0x20
task_work_run+0x98/0x100
exit_to_user_mode_prepare+0x3d0/0x3e0
syscall_exit_to_user_mode+0x12/0x30
do_syscall_64+0x42/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
Function flow analysis when BUG occurs:
f2fs_fallocate mmap
do_page_fault
pte_spinlock // ---lock_pte
do_wp_page
wp_page_shared
pte_unmap_unlock // unlock_pte
do_page_mkwrite
f2fs_vm_page_mkwrite
down_read(i_mmap_sem)
lock_page
if (PageMappedToDisk(page))
goto out;
// set_page_dirty --NOT RUN
out: up_read(i_mmap_sem)
lock_page
finish_mkwrite_fault // unlock_pte
f2fs_collapse_range
down_write(i_mmap_sem)
truncate_pagecache
unmap_mapping_pages
i_mmap_lock_write // down_write(i_mmap_rwsem)
......
zap_pte_range
pte_offset_map_lock // ---lock_pte
f2fs_set_data_page_dirty
if (!PageDirty(page)) {
fault_dirty_shared_page
f2fs_set_data_page_dirty
if (!PageDirty(page)) {
__set_page_dirty_nobuffer
f2fs_update_dirty_page // ++
}
unlock_page
__set_page_dirty_nobuffers
f2fs_update_dirty_page // page count++
}
pte_unmap_unlock // --unlock_pte
i_mmap_unlock_write // up_write(i_mmap_rwsem)
truncate_inode_pages
up_write(i_mmap_sem)
When race happens between mmap-do_page_fault-wp_page_shared and
fallocate-truncate_pagecache-zap_pte_range, the zap_pte_range calls
function set_page_dirty without page lock. Besides, though
truncate_pagecache has immap and pte lock, wp_page_shared calls
fault_dirty_shared_page without any. In this case, two threads race
in f2fs_set_data_page_dirty function. Page is set to dirty only ONCE,
but the count is added TWICE by calling f2fs_update_dirty_page.
Thus the count of dirty page cannot accord with the real dirty pages.
Following is the solution to in case of race happens without any lock.
If making sure f2fs_vm_page_mkwrite calls set_page_dirty within immap
lock area, page will already be dirtied when running into
fault_dirty_shared_page-f2fs_set_data_page_dirty.
The count of dirty page will not be increased wrong times.
Signed-off-by: Shuqi Zhang <zhangshuqi3@huawei.com>
---
fs/f2fs/file.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index ce4905a073b3..d837359a9c00 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -140,7 +140,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
* check to see if the page is mapped already (no holes)
*/
if (PageMappedToDisk(page))
- goto out_sem;
+ goto set_dirty;
/* page is wholly or partially inside EOF */
if (((loff_t)(page->index + 1) << PAGE_SHIFT) >
@@ -150,14 +150,15 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
offset = i_size_read(inode) & ~PAGE_MASK;
zero_user_segment(page, offset, PAGE_SIZE);
}
- set_page_dirty(page);
- if (!PageUptodate(page))
- SetPageUptodate(page);
f2fs_update_iostat(sbi, APP_MAPPED_IO, F2FS_BLKSIZE);
- f2fs_update_time(sbi, REQ_TIME);
+set_dirty:
trace_f2fs_vm_page_mkwrite(page, DATA);
+ set_page_dirty(page);
+ if (!PageUptodate(page))
+ SetPageUptodate(page);
+ f2fs_update_time(sbi, REQ_TIME);
out_sem:
filemap_invalidate_unlock_shared(inode->i_mapping);
--
2.25.1
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^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [f2fs-dev] [PATCH -next] f2fs: fix wrong dirty page count when race between mmap and fallocate. 2022-08-15 8:15 [f2fs-dev] [PATCH -next] f2fs: fix wrong dirty page count when race between mmap and fallocate Shuqi Zhang via Linux-f2fs-devel @ 2022-08-20 6:35 ` Chao Yu 2022-08-20 22:03 ` Jaegeuk Kim 0 siblings, 1 reply; 6+ messages in thread From: Chao Yu @ 2022-08-20 6:35 UTC (permalink / raw) To: Shuqi Zhang, jaegeuk; +Cc: linux-kernel, linux-f2fs-devel On 2022/8/15 16:15, Shuqi Zhang wrote: > This is a BUG_ON issue as follows when running xfstest-generic-503: > WARNING: CPU: 21 PID: 1385 at fs/f2fs/inode.c:762 f2fs_evict_inode+0x847/0xaa0 > Modules linked in: > CPU: 21 PID: 1385 Comm: umount Not tainted 5.19.0-rc5+ #73 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/01/2014 > > Call Trace: > evict+0x129/0x2d0 > dispose_list+0x4f/0xb0 > evict_inodes+0x204/0x230 > generic_shutdown_super+0x5b/0x1e0 > kill_block_super+0x29/0x80 > kill_f2fs_super+0xe6/0x140 > deactivate_locked_super+0x44/0xc0 > deactivate_super+0x79/0x90 > cleanup_mnt+0x114/0x1a0 > __cleanup_mnt+0x16/0x20 > task_work_run+0x98/0x100 > exit_to_user_mode_prepare+0x3d0/0x3e0 > syscall_exit_to_user_mode+0x12/0x30 > do_syscall_64+0x42/0x80 > entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > Function flow analysis when BUG occurs: > f2fs_fallocate mmap > do_page_fault > pte_spinlock // ---lock_pte > do_wp_page > wp_page_shared > pte_unmap_unlock // unlock_pte > do_page_mkwrite > f2fs_vm_page_mkwrite > down_read(i_mmap_sem) > lock_page > if (PageMappedToDisk(page)) > goto out; > // set_page_dirty --NOT RUN > out: up_read(i_mmap_sem) > lock_page > finish_mkwrite_fault // unlock_pte > f2fs_collapse_range > down_write(i_mmap_sem) > truncate_pagecache > unmap_mapping_pages > i_mmap_lock_write // down_write(i_mmap_rwsem) > ...... > zap_pte_range > pte_offset_map_lock // ---lock_pte > f2fs_set_data_page_dirty I didn't get it, why zap_pte_range() can set page dirty w/o lock_page? I found it's very easy to reproduce this bug, but previously I never saw this... is there any code udpate around truncate_pagecache()? Thanks, > if (!PageDirty(page)) { > fault_dirty_shared_page > f2fs_set_data_page_dirty > if (!PageDirty(page)) { > __set_page_dirty_nobuffer > f2fs_update_dirty_page // ++ > } > unlock_page > __set_page_dirty_nobuffers > f2fs_update_dirty_page // page count++ > } > pte_unmap_unlock // --unlock_pte > i_mmap_unlock_write // up_write(i_mmap_rwsem) > truncate_inode_pages > up_write(i_mmap_sem) > > When race happens between mmap-do_page_fault-wp_page_shared and > fallocate-truncate_pagecache-zap_pte_range, the zap_pte_range calls > function set_page_dirty without page lock. Besides, though > truncate_pagecache has immap and pte lock, wp_page_shared calls > fault_dirty_shared_page without any. In this case, two threads race > in f2fs_set_data_page_dirty function. Page is set to dirty only ONCE, > but the count is added TWICE by calling f2fs_update_dirty_page. > Thus the count of dirty page cannot accord with the real dirty pages. > > Following is the solution to in case of race happens without any lock. > If making sure f2fs_vm_page_mkwrite calls set_page_dirty within immap > lock area, page will already be dirtied when running into > fault_dirty_shared_page-f2fs_set_data_page_dirty. > The count of dirty page will not be increased wrong times. > > Signed-off-by: Shuqi Zhang <zhangshuqi3@huawei.com> > --- > fs/f2fs/file.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > index ce4905a073b3..d837359a9c00 100644 > --- a/fs/f2fs/file.c > +++ b/fs/f2fs/file.c > @@ -140,7 +140,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > * check to see if the page is mapped already (no holes) > */ > if (PageMappedToDisk(page)) > - goto out_sem; > + goto set_dirty; > > /* page is wholly or partially inside EOF */ > if (((loff_t)(page->index + 1) << PAGE_SHIFT) > > @@ -150,14 +150,15 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > offset = i_size_read(inode) & ~PAGE_MASK; > zero_user_segment(page, offset, PAGE_SIZE); > } > - set_page_dirty(page); > - if (!PageUptodate(page)) > - SetPageUptodate(page); > > f2fs_update_iostat(sbi, APP_MAPPED_IO, F2FS_BLKSIZE); > - f2fs_update_time(sbi, REQ_TIME); > > +set_dirty: > trace_f2fs_vm_page_mkwrite(page, DATA); > + set_page_dirty(page); > + if (!PageUptodate(page)) > + SetPageUptodate(page); > + f2fs_update_time(sbi, REQ_TIME); > out_sem: > filemap_invalidate_unlock_shared(inode->i_mapping); > _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [f2fs-dev] [PATCH -next] f2fs: fix wrong dirty page count when race between mmap and fallocate. 2022-08-20 6:35 ` Chao Yu @ 2022-08-20 22:03 ` Jaegeuk Kim 2022-08-20 22:19 ` Jaegeuk Kim 0 siblings, 1 reply; 6+ messages in thread From: Jaegeuk Kim @ 2022-08-20 22:03 UTC (permalink / raw) To: Chao Yu; +Cc: linux-f2fs-devel, linux-kernel, Shuqi Zhang On 08/20, Chao Yu wrote: > On 2022/8/15 16:15, Shuqi Zhang wrote: > > This is a BUG_ON issue as follows when running xfstest-generic-503: > > WARNING: CPU: 21 PID: 1385 at fs/f2fs/inode.c:762 f2fs_evict_inode+0x847/0xaa0 > > Modules linked in: > > CPU: 21 PID: 1385 Comm: umount Not tainted 5.19.0-rc5+ #73 > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/01/2014 > > > > Call Trace: > > evict+0x129/0x2d0 > > dispose_list+0x4f/0xb0 > > evict_inodes+0x204/0x230 > > generic_shutdown_super+0x5b/0x1e0 > > kill_block_super+0x29/0x80 > > kill_f2fs_super+0xe6/0x140 > > deactivate_locked_super+0x44/0xc0 > > deactivate_super+0x79/0x90 > > cleanup_mnt+0x114/0x1a0 > > __cleanup_mnt+0x16/0x20 > > task_work_run+0x98/0x100 > > exit_to_user_mode_prepare+0x3d0/0x3e0 > > syscall_exit_to_user_mode+0x12/0x30 > > do_syscall_64+0x42/0x80 > > entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > > > Function flow analysis when BUG occurs: > > f2fs_fallocate mmap > > do_page_fault > > pte_spinlock // ---lock_pte > > do_wp_page > > wp_page_shared > > pte_unmap_unlock // unlock_pte > > do_page_mkwrite > > f2fs_vm_page_mkwrite > > down_read(i_mmap_sem) > > lock_page > > if (PageMappedToDisk(page)) > > goto out; > > // set_page_dirty --NOT RUN > > out: up_read(i_mmap_sem) > > lock_page > > finish_mkwrite_fault // unlock_pte > > f2fs_collapse_range > > down_write(i_mmap_sem) > > truncate_pagecache > > unmap_mapping_pages > > i_mmap_lock_write // down_write(i_mmap_rwsem) > > ...... > > zap_pte_range > > pte_offset_map_lock // ---lock_pte > > f2fs_set_data_page_dirty > > I didn't get it, why zap_pte_range() can set page dirty w/o lock_page? > > I found it's very easy to reproduce this bug, but previously I never saw this... > is there any code udpate around truncate_pagecache()? Found this. 2637 * The caller must ensure this doesn't race with truncation. Most will 2638 * simply hold the folio lock, but e.g. zap_pte_range() calls with the 2639 * folio mapped and the pte lock held, which also locks out truncation. 2640 */ 2641 bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio) 2642 { > > Thanks, > > > if (!PageDirty(page)) { > > fault_dirty_shared_page > > f2fs_set_data_page_dirty > > if (!PageDirty(page)) { > > __set_page_dirty_nobuffer > > f2fs_update_dirty_page // ++ > > } > > unlock_page > > __set_page_dirty_nobuffers > > f2fs_update_dirty_page // page count++ > > } > > pte_unmap_unlock // --unlock_pte > > i_mmap_unlock_write // up_write(i_mmap_rwsem) > > truncate_inode_pages > > up_write(i_mmap_sem) > > > > When race happens between mmap-do_page_fault-wp_page_shared and > > fallocate-truncate_pagecache-zap_pte_range, the zap_pte_range calls > > function set_page_dirty without page lock. Besides, though > > truncate_pagecache has immap and pte lock, wp_page_shared calls > > fault_dirty_shared_page without any. In this case, two threads race > > in f2fs_set_data_page_dirty function. Page is set to dirty only ONCE, > > but the count is added TWICE by calling f2fs_update_dirty_page. > > Thus the count of dirty page cannot accord with the real dirty pages. > > > > Following is the solution to in case of race happens without any lock. > > If making sure f2fs_vm_page_mkwrite calls set_page_dirty within immap > > lock area, page will already be dirtied when running into > > fault_dirty_shared_page-f2fs_set_data_page_dirty. > > The count of dirty page will not be increased wrong times. > > > > Signed-off-by: Shuqi Zhang <zhangshuqi3@huawei.com> > > --- > > fs/f2fs/file.c | 11 ++++++----- > > 1 file changed, 6 insertions(+), 5 deletions(-) > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > index ce4905a073b3..d837359a9c00 100644 > > --- a/fs/f2fs/file.c > > +++ b/fs/f2fs/file.c > > @@ -140,7 +140,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > * check to see if the page is mapped already (no holes) > > */ > > if (PageMappedToDisk(page)) > > - goto out_sem; > > + goto set_dirty; > > /* page is wholly or partially inside EOF */ > > if (((loff_t)(page->index + 1) << PAGE_SHIFT) > > > @@ -150,14 +150,15 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > offset = i_size_read(inode) & ~PAGE_MASK; > > zero_user_segment(page, offset, PAGE_SIZE); > > } > > - set_page_dirty(page); > > - if (!PageUptodate(page)) > > - SetPageUptodate(page); > > f2fs_update_iostat(sbi, APP_MAPPED_IO, F2FS_BLKSIZE); > > - f2fs_update_time(sbi, REQ_TIME); > > +set_dirty: > > trace_f2fs_vm_page_mkwrite(page, DATA); > > + set_page_dirty(page); > > + if (!PageUptodate(page)) > > + SetPageUptodate(page); > > + f2fs_update_time(sbi, REQ_TIME); > > out_sem: > > filemap_invalidate_unlock_shared(inode->i_mapping); _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [f2fs-dev] [PATCH -next] f2fs: fix wrong dirty page count when race between mmap and fallocate. 2022-08-20 22:03 ` Jaegeuk Kim @ 2022-08-20 22:19 ` Jaegeuk Kim 2022-08-24 2:48 ` Shuqi Zhang via Linux-f2fs-devel 2022-08-25 1:41 ` Chao Yu 0 siblings, 2 replies; 6+ messages in thread From: Jaegeuk Kim @ 2022-08-20 22:19 UTC (permalink / raw) To: Chao Yu; +Cc: Shuqi Zhang, linux-kernel, linux-f2fs-devel On 08/20, Jaegeuk Kim wrote: > On 08/20, Chao Yu wrote: > > On 2022/8/15 16:15, Shuqi Zhang wrote: > > > This is a BUG_ON issue as follows when running xfstest-generic-503: > > > WARNING: CPU: 21 PID: 1385 at fs/f2fs/inode.c:762 f2fs_evict_inode+0x847/0xaa0 > > > Modules linked in: > > > CPU: 21 PID: 1385 Comm: umount Not tainted 5.19.0-rc5+ #73 > > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/01/2014 > > > > > > Call Trace: > > > evict+0x129/0x2d0 > > > dispose_list+0x4f/0xb0 > > > evict_inodes+0x204/0x230 > > > generic_shutdown_super+0x5b/0x1e0 > > > kill_block_super+0x29/0x80 > > > kill_f2fs_super+0xe6/0x140 > > > deactivate_locked_super+0x44/0xc0 > > > deactivate_super+0x79/0x90 > > > cleanup_mnt+0x114/0x1a0 > > > __cleanup_mnt+0x16/0x20 > > > task_work_run+0x98/0x100 > > > exit_to_user_mode_prepare+0x3d0/0x3e0 > > > syscall_exit_to_user_mode+0x12/0x30 > > > do_syscall_64+0x42/0x80 > > > entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > > > > > Function flow analysis when BUG occurs: > > > f2fs_fallocate mmap > > > do_page_fault > > > pte_spinlock // ---lock_pte > > > do_wp_page > > > wp_page_shared > > > pte_unmap_unlock // unlock_pte > > > do_page_mkwrite > > > f2fs_vm_page_mkwrite > > > down_read(i_mmap_sem) > > > lock_page > > > if (PageMappedToDisk(page)) > > > goto out; > > > // set_page_dirty --NOT RUN > > > out: up_read(i_mmap_sem) > > > lock_page > > > finish_mkwrite_fault // unlock_pte > > > f2fs_collapse_range > > > down_write(i_mmap_sem) > > > truncate_pagecache > > > unmap_mapping_pages > > > i_mmap_lock_write // down_write(i_mmap_rwsem) > > > ...... > > > zap_pte_range > > > pte_offset_map_lock // ---lock_pte > > > f2fs_set_data_page_dirty > > > > I didn't get it, why zap_pte_range() can set page dirty w/o lock_page? > > > > I found it's very easy to reproduce this bug, but previously I never saw this... > > is there any code udpate around truncate_pagecache()? > > Found this. > > 2637 * The caller must ensure this doesn't race with truncation. Most will > 2638 * simply hold the folio lock, but e.g. zap_pte_range() calls with the > 2639 * folio mapped and the pte lock held, which also locks out truncation. > 2640 */ > 2641 bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio) > 2642 { > > > > > Thanks, > > > > > if (!PageDirty(page)) { > > > fault_dirty_shared_page > > > f2fs_set_data_page_dirty > > > if (!PageDirty(page)) { > > > __set_page_dirty_nobuffer > > > f2fs_update_dirty_page // ++ > > > } > > > unlock_page > > > __set_page_dirty_nobuffers > > > f2fs_update_dirty_page // page count++ > > > } > > > pte_unmap_unlock // --unlock_pte > > > i_mmap_unlock_write // up_write(i_mmap_rwsem) > > > truncate_inode_pages > > > up_write(i_mmap_sem) > > > > > > When race happens between mmap-do_page_fault-wp_page_shared and > > > fallocate-truncate_pagecache-zap_pte_range, the zap_pte_range calls > > > function set_page_dirty without page lock. Besides, though > > > truncate_pagecache has immap and pte lock, wp_page_shared calls > > > fault_dirty_shared_page without any. In this case, two threads race > > > in f2fs_set_data_page_dirty function. Page is set to dirty only ONCE, > > > but the count is added TWICE by calling f2fs_update_dirty_page. > > > Thus the count of dirty page cannot accord with the real dirty pages. > > > > > > Following is the solution to in case of race happens without any lock. > > > If making sure f2fs_vm_page_mkwrite calls set_page_dirty within immap > > > lock area, page will already be dirtied when running into > > > fault_dirty_shared_page-f2fs_set_data_page_dirty. > > > The count of dirty page will not be increased wrong times. > > > > > > Signed-off-by: Shuqi Zhang <zhangshuqi3@huawei.com> > > > --- > > > fs/f2fs/file.c | 11 ++++++----- > > > 1 file changed, 6 insertions(+), 5 deletions(-) > > > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > > index ce4905a073b3..d837359a9c00 100644 > > > --- a/fs/f2fs/file.c > > > +++ b/fs/f2fs/file.c > > > @@ -140,7 +140,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > > * check to see if the page is mapped already (no holes) > > > */ > > > if (PageMappedToDisk(page)) > > > - goto out_sem; > > > + goto set_dirty; > > > /* page is wholly or partially inside EOF */ > > > if (((loff_t)(page->index + 1) << PAGE_SHIFT) > > > > @@ -150,14 +150,15 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > > offset = i_size_read(inode) & ~PAGE_MASK; > > > zero_user_segment(page, offset, PAGE_SIZE); > > > } > > > - set_page_dirty(page); > > > - if (!PageUptodate(page)) > > > - SetPageUptodate(page); > > > f2fs_update_iostat(sbi, APP_MAPPED_IO, F2FS_BLKSIZE); > > > - f2fs_update_time(sbi, REQ_TIME); > > > +set_dirty: > > > trace_f2fs_vm_page_mkwrite(page, DATA); > > > + set_page_dirty(page); > > > + if (!PageUptodate(page)) > > > + SetPageUptodate(page); Actually we don't need to call SetPageUptodate() since set_page_dirty() should do? And, it seems the call stack is out-dated as well. By the way, do we just need to get the right count by this? --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -3697,8 +3697,7 @@ static bool f2fs_dirty_data_folio(struct address_space *mapping, folio_mark_uptodate(folio); BUG_ON(folio_test_swapcache(folio)); - if (!folio_test_dirty(folio)) { - filemap_dirty_folio(mapping, folio); + if (filemap_dirty_folio(mapping, folio)) { f2fs_update_dirty_folio(inode, folio); return true; } > > > + f2fs_update_time(sbi, REQ_TIME); > > > out_sem: > > > filemap_invalidate_unlock_shared(inode->i_mapping); > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [f2fs-dev] [PATCH -next] f2fs: fix wrong dirty page count when race between mmap and fallocate. 2022-08-20 22:19 ` Jaegeuk Kim @ 2022-08-24 2:48 ` Shuqi Zhang via Linux-f2fs-devel 2022-08-25 1:41 ` Chao Yu 1 sibling, 0 replies; 6+ messages in thread From: Shuqi Zhang via Linux-f2fs-devel @ 2022-08-24 2:48 UTC (permalink / raw) To: Jaegeuk Kim, Chao Yu; +Cc: linux-kernel, linux-f2fs-devel On 08/21, Jaegeuk Kim wrote: > On 08/20, Jaegeuk Kim wrote: >> On 08/20, Chao Yu wrote: >>> On 2022/8/15 16:15, Shuqi Zhang wrote: >>>> This is a BUG_ON issue as follows when running xfstest-generic-503: >>>> WARNING: CPU: 21 PID: 1385 at fs/f2fs/inode.c:762 f2fs_evict_inode+0x847/0xaa0 >>>> Modules linked in: >>>> CPU: 21 PID: 1385 Comm: umount Not tainted 5.19.0-rc5+ #73 >>>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/01/2014 >>>> >>>> Call Trace: >>>> evict+0x129/0x2d0 >>>> dispose_list+0x4f/0xb0 >>>> evict_inodes+0x204/0x230 >>>> generic_shutdown_super+0x5b/0x1e0 >>>> kill_block_super+0x29/0x80 >>>> kill_f2fs_super+0xe6/0x140 >>>> deactivate_locked_super+0x44/0xc0 >>>> deactivate_super+0x79/0x90 >>>> cleanup_mnt+0x114/0x1a0 >>>> __cleanup_mnt+0x16/0x20 >>>> task_work_run+0x98/0x100 >>>> exit_to_user_mode_prepare+0x3d0/0x3e0 >>>> syscall_exit_to_user_mode+0x12/0x30 >>>> do_syscall_64+0x42/0x80 >>>> entry_SYSCALL_64_after_hwframe+0x46/0xb0 >>>> >>>> Function flow analysis when BUG occurs: >>>> f2fs_fallocate mmap >>>> do_page_fault >>>> pte_spinlock // ---lock_pte >>>> do_wp_page >>>> wp_page_shared >>>> pte_unmap_unlock // unlock_pte >>>> do_page_mkwrite >>>> f2fs_vm_page_mkwrite >>>> down_read(i_mmap_sem) >>>> lock_page >>>> if (PageMappedToDisk(page)) >>>> goto out; >>>> // set_page_dirty --NOT RUN >>>> out: up_read(i_mmap_sem) >>>> lock_page >>>> finish_mkwrite_fault // unlock_pte >>>> f2fs_collapse_range >>>> down_write(i_mmap_sem) >>>> truncate_pagecache >>>> unmap_mapping_pages >>>> i_mmap_lock_write // down_write(i_mmap_rwsem) >>>> ...... >>>> zap_pte_range >>>> pte_offset_map_lock // ---lock_pte >>>> f2fs_set_data_page_dirty >>> I didn't get it, why zap_pte_range() can set page dirty w/o lock_page? >>> >>> I found it's very easy to reproduce this bug, but previously I never saw this... >>> is there any code udpate around truncate_pagecache()? >> Found this. >> >> 2637 * The caller must ensure this doesn't race with truncation. Most will >> 2638 * simply hold the folio lock, but e.g. zap_pte_range() calls with the >> 2639 * folio mapped and the pte lock held, which also locks out truncation. >> 2640 */ >> 2641 bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio) >> 2642 { >> >>> Thanks, >>> >>>> if (!PageDirty(page)) { >>>> fault_dirty_shared_page >>>> f2fs_set_data_page_dirty >>>> if (!PageDirty(page)) { >>>> __set_page_dirty_nobuffer >>>> f2fs_update_dirty_page // ++ >>>> } >>>> unlock_page >>>> __set_page_dirty_nobuffers >>>> f2fs_update_dirty_page // page count++ >>>> } >>>> pte_unmap_unlock // --unlock_pte >>>> i_mmap_unlock_write // up_write(i_mmap_rwsem) >>>> truncate_inode_pages >>>> up_write(i_mmap_sem) >>>> >>>> When race happens between mmap-do_page_fault-wp_page_shared and >>>> fallocate-truncate_pagecache-zap_pte_range, the zap_pte_range calls >>>> function set_page_dirty without page lock. Besides, though >>>> truncate_pagecache has immap and pte lock, wp_page_shared calls >>>> fault_dirty_shared_page without any. In this case, two threads race >>>> in f2fs_set_data_page_dirty function. Page is set to dirty only ONCE, >>>> but the count is added TWICE by calling f2fs_update_dirty_page. >>>> Thus the count of dirty page cannot accord with the real dirty pages. >>>> >>>> Following is the solution to in case of race happens without any lock. >>>> If making sure f2fs_vm_page_mkwrite calls set_page_dirty within immap >>>> lock area, page will already be dirtied when running into >>>> fault_dirty_shared_page-f2fs_set_data_page_dirty. >>>> The count of dirty page will not be increased wrong times. >>>> >>>> Signed-off-by: Shuqi Zhang <zhangshuqi3@huawei.com> >>>> --- >>>> fs/f2fs/file.c | 11 ++++++----- >>>> 1 file changed, 6 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >>>> index ce4905a073b3..d837359a9c00 100644 >>>> --- a/fs/f2fs/file.c >>>> +++ b/fs/f2fs/file.c >>>> @@ -140,7 +140,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) >>>> * check to see if the page is mapped already (no holes) >>>> */ >>>> if (PageMappedToDisk(page)) >>>> - goto out_sem; >>>> + goto set_dirty; >>>> /* page is wholly or partially inside EOF */ >>>> if (((loff_t)(page->index + 1) << PAGE_SHIFT) > >>>> @@ -150,14 +150,15 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) >>>> offset = i_size_read(inode) & ~PAGE_MASK; >>>> zero_user_segment(page, offset, PAGE_SIZE); >>>> } >>>> - set_page_dirty(page); >>>> - if (!PageUptodate(page)) >>>> - SetPageUptodate(page); >>>> f2fs_update_iostat(sbi, APP_MAPPED_IO, F2FS_BLKSIZE); >>>> - f2fs_update_time(sbi, REQ_TIME); >>>> +set_dirty: >>>> trace_f2fs_vm_page_mkwrite(page, DATA); >>>> + set_page_dirty(page); >>>> + if (!PageUptodate(page)) >>>> + SetPageUptodate(page); > Actually we don't need to call SetPageUptodate() since set_page_dirty() should > do? And, it seems the call stack is out-dated as well. > > By the way, do we just need to get the right count by this? > > --- a/fs/f2fs/data.c > +++ b/fs/f2fs/data.c > @@ -3697,8 +3697,7 @@ static bool f2fs_dirty_data_folio(struct address_space *mapping, > folio_mark_uptodate(folio); > BUG_ON(folio_test_swapcache(folio)); > > - if (!folio_test_dirty(folio)) { > - filemap_dirty_folio(mapping, folio); > + if (filemap_dirty_folio(mapping, folio)) { > f2fs_update_dirty_folio(inode, folio); > return true; > } Yes, this patch seems a better one. I will send a PATCH-v2 about it. Thanks, >>>> + f2fs_update_time(sbi, REQ_TIME); >>>> out_sem: >>>> filemap_invalidate_unlock_shared(inode->i_mapping); >> >> _______________________________________________ >> Linux-f2fs-devel mailing list >> Linux-f2fs-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [f2fs-dev] [PATCH -next] f2fs: fix wrong dirty page count when race between mmap and fallocate. 2022-08-20 22:19 ` Jaegeuk Kim 2022-08-24 2:48 ` Shuqi Zhang via Linux-f2fs-devel @ 2022-08-25 1:41 ` Chao Yu 1 sibling, 0 replies; 6+ messages in thread From: Chao Yu @ 2022-08-25 1:41 UTC (permalink / raw) To: Jaegeuk Kim; +Cc: Shuqi Zhang, linux-kernel, linux-f2fs-devel On 2022/8/21 6:19, Jaegeuk Kim wrote: > On 08/20, Jaegeuk Kim wrote: >> On 08/20, Chao Yu wrote: >>> On 2022/8/15 16:15, Shuqi Zhang wrote: >>>> This is a BUG_ON issue as follows when running xfstest-generic-503: >>>> WARNING: CPU: 21 PID: 1385 at fs/f2fs/inode.c:762 f2fs_evict_inode+0x847/0xaa0 >>>> Modules linked in: >>>> CPU: 21 PID: 1385 Comm: umount Not tainted 5.19.0-rc5+ #73 >>>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/01/2014 >>>> >>>> Call Trace: >>>> evict+0x129/0x2d0 >>>> dispose_list+0x4f/0xb0 >>>> evict_inodes+0x204/0x230 >>>> generic_shutdown_super+0x5b/0x1e0 >>>> kill_block_super+0x29/0x80 >>>> kill_f2fs_super+0xe6/0x140 >>>> deactivate_locked_super+0x44/0xc0 >>>> deactivate_super+0x79/0x90 >>>> cleanup_mnt+0x114/0x1a0 >>>> __cleanup_mnt+0x16/0x20 >>>> task_work_run+0x98/0x100 >>>> exit_to_user_mode_prepare+0x3d0/0x3e0 >>>> syscall_exit_to_user_mode+0x12/0x30 >>>> do_syscall_64+0x42/0x80 >>>> entry_SYSCALL_64_after_hwframe+0x46/0xb0 >>>> >>>> Function flow analysis when BUG occurs: >>>> f2fs_fallocate mmap >>>> do_page_fault >>>> pte_spinlock // ---lock_pte >>>> do_wp_page >>>> wp_page_shared >>>> pte_unmap_unlock // unlock_pte >>>> do_page_mkwrite >>>> f2fs_vm_page_mkwrite >>>> down_read(i_mmap_sem) >>>> lock_page >>>> if (PageMappedToDisk(page)) >>>> goto out; >>>> // set_page_dirty --NOT RUN >>>> out: up_read(i_mmap_sem) >>>> lock_page >>>> finish_mkwrite_fault // unlock_pte >>>> f2fs_collapse_range >>>> down_write(i_mmap_sem) >>>> truncate_pagecache >>>> unmap_mapping_pages >>>> i_mmap_lock_write // down_write(i_mmap_rwsem) >>>> ...... >>>> zap_pte_range >>>> pte_offset_map_lock // ---lock_pte >>>> f2fs_set_data_page_dirty >>> >>> I didn't get it, why zap_pte_range() can set page dirty w/o lock_page? >>> >>> I found it's very easy to reproduce this bug, but previously I never saw this... >>> is there any code udpate around truncate_pagecache()? >> >> Found this. >> >> 2637 * The caller must ensure this doesn't race with truncation. Most will >> 2638 * simply hold the folio lock, but e.g. zap_pte_range() calls with the >> 2639 * folio mapped and the pte lock held, which also locks out truncation. >> 2640 */ >> 2641 bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio) >> 2642 { >> >>> >>> Thanks, >>> >>>> if (!PageDirty(page)) { >>>> fault_dirty_shared_page >>>> f2fs_set_data_page_dirty >>>> if (!PageDirty(page)) { >>>> __set_page_dirty_nobuffer >>>> f2fs_update_dirty_page // ++ >>>> } >>>> unlock_page >>>> __set_page_dirty_nobuffers >>>> f2fs_update_dirty_page // page count++ >>>> } >>>> pte_unmap_unlock // --unlock_pte >>>> i_mmap_unlock_write // up_write(i_mmap_rwsem) >>>> truncate_inode_pages >>>> up_write(i_mmap_sem) >>>> >>>> When race happens between mmap-do_page_fault-wp_page_shared and >>>> fallocate-truncate_pagecache-zap_pte_range, the zap_pte_range calls >>>> function set_page_dirty without page lock. Besides, though >>>> truncate_pagecache has immap and pte lock, wp_page_shared calls >>>> fault_dirty_shared_page without any. In this case, two threads race >>>> in f2fs_set_data_page_dirty function. Page is set to dirty only ONCE, >>>> but the count is added TWICE by calling f2fs_update_dirty_page. >>>> Thus the count of dirty page cannot accord with the real dirty pages. >>>> >>>> Following is the solution to in case of race happens without any lock. >>>> If making sure f2fs_vm_page_mkwrite calls set_page_dirty within immap >>>> lock area, page will already be dirtied when running into >>>> fault_dirty_shared_page-f2fs_set_data_page_dirty. >>>> The count of dirty page will not be increased wrong times. >>>> >>>> Signed-off-by: Shuqi Zhang <zhangshuqi3@huawei.com> >>>> --- >>>> fs/f2fs/file.c | 11 ++++++----- >>>> 1 file changed, 6 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >>>> index ce4905a073b3..d837359a9c00 100644 >>>> --- a/fs/f2fs/file.c >>>> +++ b/fs/f2fs/file.c >>>> @@ -140,7 +140,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) >>>> * check to see if the page is mapped already (no holes) >>>> */ >>>> if (PageMappedToDisk(page)) >>>> - goto out_sem; >>>> + goto set_dirty; >>>> /* page is wholly or partially inside EOF */ >>>> if (((loff_t)(page->index + 1) << PAGE_SHIFT) > >>>> @@ -150,14 +150,15 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) >>>> offset = i_size_read(inode) & ~PAGE_MASK; >>>> zero_user_segment(page, offset, PAGE_SIZE); >>>> } >>>> - set_page_dirty(page); >>>> - if (!PageUptodate(page)) >>>> - SetPageUptodate(page); >>>> f2fs_update_iostat(sbi, APP_MAPPED_IO, F2FS_BLKSIZE); >>>> - f2fs_update_time(sbi, REQ_TIME); >>>> +set_dirty: >>>> trace_f2fs_vm_page_mkwrite(page, DATA); >>>> + set_page_dirty(page); >>>> + if (!PageUptodate(page)) >>>> + SetPageUptodate(page); > > Actually we don't need to call SetPageUptodate() since set_page_dirty() should > do? And, it seems the call stack is out-dated as well. > > By the way, do we just need to get the right count by this? > > --- a/fs/f2fs/data.c > +++ b/fs/f2fs/data.c > @@ -3697,8 +3697,7 @@ static bool f2fs_dirty_data_folio(struct address_space *mapping, > folio_mark_uptodate(folio); > BUG_ON(folio_test_swapcache(folio)); > > - if (!folio_test_dirty(folio)) { > - filemap_dirty_folio(mapping, folio); > + if (filemap_dirty_folio(mapping, folio)) { Agreed, how about checking return value of filemap_dirty_folio() in f2fs_dirty_{meta,node}_folio as well for cleanup. > f2fs_update_dirty_folio(inode, folio); > return true; I suspect we may still suffer from below race condition? due to we will access/update page private stuff w/o page lock in zap_pte_range. - zap_pte_range - f2fs_defragment_range - f2fs_dirty_data_folio - f2fs_update_dirty_folio - lock_page - set_page_private_reference - set_page_private_gcing Thanks, > } > >>>> + f2fs_update_time(sbi, REQ_TIME); >>>> out_sem: >>>> filemap_invalidate_unlock_shared(inode->i_mapping); >> >> >> _______________________________________________ >> Linux-f2fs-devel mailing list >> Linux-f2fs-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-08-25 1:41 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2022-08-15 8:15 [f2fs-dev] [PATCH -next] f2fs: fix wrong dirty page count when race between mmap and fallocate Shuqi Zhang via Linux-f2fs-devel 2022-08-20 6:35 ` Chao Yu 2022-08-20 22:03 ` Jaegeuk Kim 2022-08-20 22:19 ` Jaegeuk Kim 2022-08-24 2:48 ` Shuqi Zhang via Linux-f2fs-devel 2022-08-25 1:41 ` Chao Yu
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