On Sat, Sep 9, 2023 at 6:04 AM <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > The patch below does not apply to the 6.1-stable tree. > If someone wants it applied there, or to any other stable or longterm > tree, then please email the backport, including the original git commit > id to <stable@xxxxxxxxxxxxxxx>. > > To reproduce the conflict and resubmit, you may use the following commands: > > git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y > git checkout FETCH_HEAD > git cherry-pick -x 669281ee7ef731fb5204df9d948669bf32a5e68d > # <resolve conflicts, build, test, etc.> > git commit -s > git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2023090959-mothproof-scarf-6195@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. > > Possible dependencies: > > 669281ee7ef7 ("Multi-gen LRU: fix per-zone reclaim") > 6df1b2212950 ("mm: multi-gen LRU: rename lrugen->lists[] to lrugen->folios[]") Hi Greg, Can you apply in this order please: 1) 6df1b2212950 ("mm: multi-gen LRU: rename lrugen->lists[] to lrugen->folios[]") 2) 669281ee7ef7 ("Multi-gen LRU: fix per-zone reclaim") With the one rename dependency, I've checked that this applies cleanly and tested it. Or let me know if you prefer I resend both. Thanks, Kalesh > > thanks, > > greg k-h > > ------------------ original commit in Linus's tree ------------------ > > From 669281ee7ef731fb5204df9d948669bf32a5e68d Mon Sep 17 00:00:00 2001 > From: Kalesh Singh <kaleshsingh@xxxxxxxxxx> > Date: Tue, 1 Aug 2023 19:56:02 -0700 > Subject: [PATCH] Multi-gen LRU: fix per-zone reclaim > > MGLRU has a LRU list for each zone for each type (anon/file) in each > generation: > > long nr_pages[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES]; > > The min_seq (oldest generation) can progress independently for each > type but the max_seq (youngest generation) is shared for both anon and > file. This is to maintain a common frame of reference. > > In order for eviction to advance the min_seq of a type, all the per-zone > lists in the oldest generation of that type must be empty. > > The eviction logic only considers pages from eligible zones for > eviction or promotion. > > scan_folios() { > ... > for (zone = sc->reclaim_idx; zone >= 0; zone--) { > ... > sort_folio(); // Promote > ... > isolate_folio(); // Evict > } > ... > } > > Consider the system has the movable zone configured and default 4 > generations. The current state of the system is as shown below > (only illustrating one type for simplicity): > > Type: ANON > > Zone DMA32 Normal Movable Device > > Gen 0 0 0 4GB 0 > > Gen 1 0 1GB 1MB 0 > > Gen 2 1MB 4GB 1MB 0 > > Gen 3 1MB 1MB 1MB 0 > > Now consider there is a GFP_KERNEL allocation request (eligible zone > index <= Normal), evict_folios() will return without doing any work > since there are no pages to scan in the eligible zones of the oldest > generation. Reclaim won't make progress until triggered from a ZONE_MOVABLE > allocation request; which may not happen soon if there is a lot of free > memory in the movable zone. This can lead to OOM kills, although there > is 1GB pages in the Normal zone of Gen 1 that we have not yet tried to > reclaim. > > This issue is not seen in the conventional active/inactive LRU since > there are no per-zone lists. > > If there are no (not enough) folios to scan in the eligible zones, move > folios from ineligible zone (zone_index > reclaim_index) to the next > generation. This allows for the progression of min_seq and reclaiming > from the next generation (Gen 1). > > Qualcomm, Mediatek and raspberrypi [1] discovered this issue independently. > > [1] https://github.com/raspberrypi/linux/issues/5395 > > Link: https://lkml.kernel.org/r/20230802025606.346758-1-kaleshsingh@xxxxxxxxxx > Fixes: ac35a4902374 ("mm: multi-gen LRU: minimal implementation") > Signed-off-by: Kalesh Singh <kaleshsingh@xxxxxxxxxx> > Reported-by: Charan Teja Kalla <quic_charante@xxxxxxxxxxx> > Reported-by: Lecopzer Chen <lecopzer.chen@xxxxxxxxxxxx> > Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx> [mediatek] > Tested-by: Charan Teja Kalla <quic_charante@xxxxxxxxxxx> > Cc: Yu Zhao <yuzhao@xxxxxxxxxx> > Cc: Barry Song <baohua@xxxxxxxxxx> > Cc: Brian Geffon <bgeffon@xxxxxxxxxx> > Cc: Jan Alexander Steffens (heftig) <heftig@xxxxxxxxxxxxx> > Cc: Matthias Brugger <matthias.bgg@xxxxxxxxx> > Cc: Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx> > Cc: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> > Cc: Steven Barrett <steven@xxxxxxxxxxxx> > Cc: Suleiman Souhlal <suleiman@xxxxxxxxxx> > Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx> > Cc: Aneesh Kumar K V <aneesh.kumar@xxxxxxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 4039620d30fe..489a4fc7d9b1 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -4889,7 +4889,8 @@ static int lru_gen_memcg_seg(struct lruvec *lruvec) > * the eviction > ******************************************************************************/ > > -static bool sort_folio(struct lruvec *lruvec, struct folio *folio, int tier_idx) > +static bool sort_folio(struct lruvec *lruvec, struct folio *folio, struct scan_control *sc, > + int tier_idx) > { > bool success; > int gen = folio_lru_gen(folio); > @@ -4939,6 +4940,13 @@ static bool sort_folio(struct lruvec *lruvec, struct folio *folio, int tier_idx) > return true; > } > > + /* ineligible */ > + if (zone > sc->reclaim_idx) { > + gen = folio_inc_gen(lruvec, folio, false); > + list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]); > + return true; > + } > + > /* waiting for writeback */ > if (folio_test_locked(folio) || folio_test_writeback(folio) || > (type == LRU_GEN_FILE && folio_test_dirty(folio))) { > @@ -4987,7 +4995,8 @@ static bool isolate_folio(struct lruvec *lruvec, struct folio *folio, struct sca > static int scan_folios(struct lruvec *lruvec, struct scan_control *sc, > int type, int tier, struct list_head *list) > { > - int gen, zone; > + int i; > + int gen; > enum vm_event_item item; > int sorted = 0; > int scanned = 0; > @@ -5003,9 +5012,10 @@ static int scan_folios(struct lruvec *lruvec, struct scan_control *sc, > > gen = lru_gen_from_seq(lrugen->min_seq[type]); > > - for (zone = sc->reclaim_idx; zone >= 0; zone--) { > + for (i = MAX_NR_ZONES; i > 0; i--) { > LIST_HEAD(moved); > int skipped = 0; > + int zone = (sc->reclaim_idx + i) % MAX_NR_ZONES; > struct list_head *head = &lrugen->folios[gen][type][zone]; > > while (!list_empty(head)) { > @@ -5019,7 +5029,7 @@ static int scan_folios(struct lruvec *lruvec, struct scan_control *sc, > > scanned += delta; > > - if (sort_folio(lruvec, folio, tier)) > + if (sort_folio(lruvec, folio, sc, tier)) > sorted += delta; > else if (isolate_folio(lruvec, folio, sc)) { > list_add(&folio->lru, list); >
