On Thu, 29 Aug 2024, Baolin Wang wrote: > On 2024/8/29 16:07, Hugh Dickins wrote: ... > > > > Fix below. Successful testing on mm-everything-2024-08-24-07-21 (well, > > that minus the commit which spewed warnings from bootup) confirmed it. > > But testing on mm-everything-2024-08-28-21-38 very quickly failed: > > unrelated to this series, presumably caused by patch or patches added > > since 08-24, one kind of crash on one machine (some memcg thing called > > from isolate_migratepages_block), another kind of crash on another (some > > memcg thing called from __read_swap_cache_async), I'm exhausted by now > > but will investigate later in the day (or hope someone else has). > > I saw the isolate_migratepages_block crash issue on > mm-everything-2024-08-28-09-32, and I reverted Kefeng's series "[PATCH 0/4] > mm: convert to folio_isolate_movable()", the isolate_migratepages_block issue > seems to be resolved (at least I can not reproduce it). > > And I have already pointed out some potential issues in Kefeng’s series[1]. > Andrew has dropped this series from mm-everything-2024-08-28-21-38. However, > you can still encounter the isolate_migratepages_block issue on > mm-everything-2024-08-28-21-38, while I cannot, weird. It was not that issue: isolate_migratepages_block() turned out to be an innocent bystander in my case: and I didn't see it crash there again, but in a variety of other memcg places, many of them stat updates. The error came from a different series, fix now posted: https://lore.kernel.org/linux-mm/56d42242-37fe-b94f-d3cb-00673f1e5efb@xxxxxxxxxx/T/#u > > > [PATCH] mm: filemap: use xa_get_order() to get the swap entry order: fix > > > > find_lock_entries(), used in the first pass of shmem_undo_range() and > > truncate_inode_pages_range() before partial folios are dealt with, has > > to be careful to avoid those partial folios: as its doc helpfully says, > > "Folios which are partially outside the range are not returned". Of > > course, the same must be true of any value entries returned, otherwise > > truncation and hole-punch risk erasing swapped areas - as has been seen. > > > > Rewrite find_lock_entries() to emphasize that, following the same pattern > > for folios and for value entries. > > > > Adjust find_get_entries() slightly, to get order while still holding > > rcu_read_lock(), and to round down the updated start: good changes, like > > find_lock_entries() now does, but it's unclear if either is ever important. > > > > Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx> > > Thanks Hugh. The changes make sense to me. Thanks! Hugh
