On Tue, Jun 11, 2024 at 10:10 PM Hugh Dickins <hughd@xxxxxxxxxx> wrote: > > /proc/meminfo is showing ridiculously large numbers on some lines: > __folio_remove_rmap()'s __folio_mod_stat() should be subtracting! > > Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx> Reviewed-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx> Thanks a lot for fixing this! I was just looking at a test failure report by the kernel robot caused by this [1]. Just to document my own stupidity here: 1. In [2], I sent a fix to use __mod_node_page_state() instead of __lruvec_stat_mod_folio() in __folio_remove_rmap(). I made the same mistake of replacing subtraction with addition. 2. In [3], I sent a v2 of that fix that kept the subtraction in __folio_remove_rmap() correctly. 3. In [4], I sent a cleanup on top of the fix, and that cleanup replaced the subtraction in __folio_remove_rmap() with an addition, again. Apparently, I just suck at subtraction :) [1]https://lore.kernel.org/linux-mm/202406121026.579593f2-oliver.sang@xxxxxxxxx/ [2]https://lore.kernel.org/lkml/20240506170024.202111-1-yosryahmed@xxxxxxxxxx/ [3]https://lore.kernel.org/lkml/20240506192924.271999-1-yosryahmed@xxxxxxxxxx/ [4]https://lore.kernel.org/lkml/20240506211333.346605-1-yosryahmed@xxxxxxxxxx/ > --- > A fix for folding into mm-unstable, not needed for 6.10-rc. > > mm/rmap.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1567,7 +1567,7 @@ static __always_inline void __folio_remove_rmap(struct folio *folio, > list_empty(&folio->_deferred_list)) > deferred_split_folio(folio); > } > - __folio_mod_stat(folio, nr, nr_pmdmapped); > + __folio_mod_stat(folio, -nr, -nr_pmdmapped); > > /* > * It would be tidy to reset folio_test_anon mapping when fully > -- > 2.35.3 >
