On 2023/10/30 22:56, Trond Myklebust wrote:
A refactoring is by definition a change that does not affect code
behaviour. It is obvious that this was never intended to be such a
patch.
The reason that the bug is occurring in 4.19.x, and not in the latest
kernels, is because the former is missing another bugfix (one which
actually is missing a "Fixes:" tag).
Can you therefore please check if applying commit 22876f540bdf ("NFS:
Don't call generic_error_remove_page() while holding locks") fixes the
issue.
Note that the latter patch is needed in any case in order to fix a read
deadlock (as indicated on the label).
Thanks,
Trond
Sorry, the previous email had formatting issues. I'll resend it.
After applying commit 22876f540bdf ("NFS: Don't call
generic_error_remove_page() while holding locks"), I encountered an
issue of infinite loop:
write
...
nfs_updatepage
nfs_writepage_setup
nfs_setup_write_request
nfs_try_to_update_request
nfs_wb_page
if (clear_page_dirty_for_io(page)) // true
nfs_writepage_locked // return 0
nfs_do_writepage // return 0
nfs_page_async_flush // return 0
nfs_error_is_fatal_on_server
nfs_write_error_remove_page
SetPageError // instead of generic_error_remove_page
// loop begin
if (clear_page_dirty_for_io(page)) // false
if (!PagePrivate(page)) // false
ret = nfs_commit_inode = 0
// loop again, never quit
before applying commit 22876f540bdf ("NFS: Don't call
generic_error_remove_page() while holding locks"),
generic_error_remove_page() will clear PG_private, and infinite loop
will never happen:
generic_error_remove_page
truncate_inode_page
truncate_cleanup_page
do_invalidatepage
nfs_invalidate_page
nfs_wb_page_cancel
nfs_inode_remove_request
ClearPagePrivate(head->wb_page)
If applying this patch, are other patches required? And I cannot
reproducethe read deadlock bug that the patch want to fix, are there
specific conditions required to reproduce this read deadlock bug?
