| Message ID | 20220329132619.18689-5-linmiaohe@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | A few cleanup and fixup patches for migration | expand |
On Tue, Mar 29, 2022 at 09:26:15PM +0800, Miaohe Lin wrote: > LRU_UNEVICTABLE is not taken into account when shrink lruvec. So we can > save a bit of stack space by shrinking the array size of nr and targets > to NR_LRU_LISTS - 1. No functional change intended. > > Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> > --- > mm/vmscan.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index a6e60c78d058..ebd8ffb63673 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2862,8 +2862,9 @@ static bool can_age_anon_pages(struct pglist_data *pgdat, > > static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) > { > - unsigned long nr[NR_LRU_LISTS]; > - unsigned long targets[NR_LRU_LISTS]; > + /* LRU_UNEVICTABLE is not taken into account. */ > + unsigned long nr[NR_LRU_LISTS - 1]; > + unsigned long targets[NR_LRU_LISTS - 1]; This looks like a problem waiting to happen..
On 2022/3/29 22:00, Christoph Hellwig wrote: > On Tue, Mar 29, 2022 at 09:26:15PM +0800, Miaohe Lin wrote: >> LRU_UNEVICTABLE is not taken into account when shrink lruvec. So we can >> save a bit of stack space by shrinking the array size of nr and targets >> to NR_LRU_LISTS - 1. No functional change intended. >> >> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> >> --- >> mm/vmscan.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/mm/vmscan.c b/mm/vmscan.c >> index a6e60c78d058..ebd8ffb63673 100644 >> --- a/mm/vmscan.c >> +++ b/mm/vmscan.c >> @@ -2862,8 +2862,9 @@ static bool can_age_anon_pages(struct pglist_data *pgdat, >> >> static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) >> { >> - unsigned long nr[NR_LRU_LISTS]; >> - unsigned long targets[NR_LRU_LISTS]; >> + /* LRU_UNEVICTABLE is not taken into account. */ >> + unsigned long nr[NR_LRU_LISTS - 1]; >> + unsigned long targets[NR_LRU_LISTS - 1]; > > This looks like a problem waiting to happen.. IIUC, I am changing the array size to what it exactly uses now. And LRU_UNEVICTABLE won't be used anyway. Could you please tell me what kind of problem is waiting to happen ? If this will result in actual risk, I will drop this patch. Thanks. > > . >
diff --git a/mm/vmscan.c b/mm/vmscan.c index a6e60c78d058..ebd8ffb63673 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2862,8 +2862,9 @@ static bool can_age_anon_pages(struct pglist_data *pgdat, static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) { - unsigned long nr[NR_LRU_LISTS]; - unsigned long targets[NR_LRU_LISTS]; + /* LRU_UNEVICTABLE is not taken into account. */ + unsigned long nr[NR_LRU_LISTS - 1]; + unsigned long targets[NR_LRU_LISTS - 1]; unsigned long nr_to_scan; enum lru_list lru; unsigned long nr_reclaimed = 0;
LRU_UNEVICTABLE is not taken into account when shrink lruvec. So we can save a bit of stack space by shrinking the array size of nr and targets to NR_LRU_LISTS - 1. No functional change intended. Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> --- mm/vmscan.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)