It is noticed that during a global reclaim the memory reclaimed via shrinking the slabs can sometimes result in reclaimed pages being greater than the scanned pages in shrink_node. When this is passed to vmpressure, the unsigned arithmetic results in the pressure value to be huge, thus resulting in a critical event being sent to root cgroup. While this can be fixed by underflow checks in vmpressure, adding reclaimed slab without a corresponding increment of nr_scanned results in incorrect vmpressure reporting. So do not consider reclaimed slab pages in vmpressure calculation.
Signed-off-by: Vinayak Menon <[email protected]> --- mm/vmscan.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 947ab6f..37c4486 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2594,16 +2594,16 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) sc->nr_scanned - nr_scanned, node_lru_pages); - if (reclaim_state) { - sc->nr_reclaimed += reclaim_state->reclaimed_slab; - reclaim_state->reclaimed_slab = 0; - } - /* Record the subtree's reclaim efficiency */ vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true, sc->nr_scanned - nr_scanned, sc->nr_reclaimed - nr_reclaimed); + if (reclaim_state) { + sc->nr_reclaimed += reclaim_state->reclaimed_slab; + reclaim_state->reclaimed_slab = 0; + } + if (sc->nr_reclaimed - nr_reclaimed) reclaimable = true; -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation
