Message ID | 20230802001938.3913174-2-kaleshsingh@google.com (mailing list archive) |
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State | New |
Headers | show
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Tue, 01 Aug 2023 17:19:55 -0700 (PDT) Date: Tue, 1 Aug 2023 17:19:36 -0700 In-Reply-To: <20230802001938.3913174-1-kaleshsingh@google.com> Mime-Version: 1.0 References: <20230802001938.3913174-1-kaleshsingh@google.com> X-Mailer: git-send-email 2.41.0.255.g8b1d071c50-goog Message-ID: <20230802001938.3913174-2-kaleshsingh@google.com> Subject: [PATCH 2/3] mm-unstable: Multi-gen LRU: Avoid race in inc_min_seq() From: Kalesh Singh <kaleshsingh@google.com> To: yuzhao@google.com, akpm@linux-foundation.org Cc: surenb@google.com, android-mm@google.com, kernel-team@android.com, Kalesh Singh <kaleshsingh@google.com>, Aneesh Kumar K V <aneesh.kumar@linux.ibm.com>, Matthias Brugger <matthias.bgg@gmail.com>, AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 50499A0004 X-Stat-Signature: 9n9cg518c3gapphrdpid5jfg9jwpbrrf X-Rspam-User: X-HE-Tag: 1690935596-383757 X-HE-Meta: U2FsdGVkX197AnyuCw5I6Bu9j+pZZnUpGBabuLaxiUV13E6uWkKeHQMsf320vdDuyWDXF64/KR+/yuUYyA6vb9b0YyTmTl6L/E5kV9On71nzobchzxmfwXmf5ML+tmNb4hcqyOomNJ/KWCKldmzqJpJjRhszvDahk1xjsYd8uvHSt3RYqtEfk1j71Mb+ZNyaLqrRUwCYOSo0t0OKyRgZN71m7xmO/JxmbDB6H/wCcMR8XnONYko6nLogmiUjHWx97N0n1+EaQAwRzFfTbOicC5sdIMdxRVQojLK+zpW6Escg+d+lGBJBXHk28PMj+flGm1AfGucOBmg+DULD848U1WLOy4JKSV8X/O20PzfReKw7H8VWxcJrD4jHyrkzB+8wEweYAT8aaBZChsxqBzK7d2fjPQDB1NAVNomv9M2ag9Ijs95H4ZZ/jD8g0W8A6GODHwdl/18ZssN/aIzpxJC3Wteplm+v7LhMAslNBblQ39p0qq/FwTwyPnPBR9eOgPGIisi2xLV9l+qVlLUWaX1VceEQwTZO+UHOFJROIeLszYrD98yOLAA+WLODiWVM/PjNsJxI2p8Mrnrp7u7FDkA40E5hp8FIhxUqfONkHYTLS/BOTOkmrcAgOf5SMRiLztNFxQFbxnQynir32LkJv/DsGaDkLQOflibAZHVLEpcA14PdA0cZpdErs4kbDnPYZoUXNKB/Mga+OMQtN7WS5C4JXKeOE3N3zNlmpUReuLqZwxELiBt/x1sVKbj8wxkOnP68N5M4RsfGm4onsuFcNsbv+T+LANTgmdfgooznyJ/DKuOgBtK/Ru6NY0Jv5r4vVEAzMHi0iic8/dvOEC++IpdUc7vL7fiWXklTfOzVI8Lx1XqbOtcR7lEusiB82W/jltBKfJOotetu8e8ELqulRkot2YdAcNdEYxDNb4oDjZIWUpl2/iUuxNDvz01N34hYR2vLsyUXkMBJUNPVXvZfOdl gHgRrShH 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000017, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: <linux-mm.kvack.org> |
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[1/3] mm-unstable: Multi-gen LRU: Fix per-zone reclaim
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diff --git a/mm/vmscan.c b/mm/vmscan.c index 489a4fc7d9b1..6eecd291756c 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4439,7 +4439,7 @@ static void inc_max_seq(struct lruvec *lruvec, bool can_swap, bool force_scan) int prev, next; int type, zone; struct lru_gen_folio *lrugen = &lruvec->lrugen; - +restart: spin_lock_irq(&lruvec->lru_lock); VM_WARN_ON_ONCE(!seq_is_valid(lruvec)); @@ -4450,11 +4450,12 @@ static void inc_max_seq(struct lruvec *lruvec, bool can_swap, bool force_scan) VM_WARN_ON_ONCE(!force_scan && (type == LRU_GEN_FILE || can_swap)); - while (!inc_min_seq(lruvec, type, can_swap)) { - spin_unlock_irq(&lruvec->lru_lock); - cond_resched(); - spin_lock_irq(&lruvec->lru_lock); - } + if (inc_min_seq(lruvec, type, can_swap)) + continue; + + spin_unlock_irq(&lruvec->lru_lock); + cond_resched(); + goto restart; } /*
inc_max_seq() will try to inc_min_seq() if nr_gens == MAX_NR_GENS. This is because the generations are reused (the last oldest now empty generation will become the next youngest generation). inc_min_seq() is retried until successful, dropping the lru_lock and yielding the CPU on each failure, and retaking the lock before trying again: while (!inc_min_seq(lruvec, type, can_swap)) { spin_unlock_irq(&lruvec->lru_lock); cond_resched(); spin_lock_irq(&lruvec->lru_lock); } However, the initial condition that required incrementing the min_seq (nr_gens == MAX_NR_GENS) is not retested. This can change by another call to inc_max_seq() from run_aging() with force_scan=true from the debugfs interface. Since the eviction stalls when the nr_gens == MIN_NR_GENS, avoid unnecessarily incrementing the min_seq by rechecking the number of generations before each attempt. This issue was uncovered in previous discussion on the list by Yu Zhao and Aneesh Kumar [1]. [1] https://lore.kernel.org/linux-mm/CAOUHufbO7CaVm=xjEb1avDhHVvnC8pJmGyKcFf2iY_dpf+zR3w@mail.gmail.com/ Cc: Yu Zhao <yuzhao@google.com> Cc: Aneesh Kumar K V <aneesh.kumar@linux.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Kalesh Singh <kaleshsingh@google.com> --- mm/vmscan.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)