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AJvYcCW1LF7blZmd0hqWrC+FOxJbc83R5brczLDcmkCowBrozODNbrVJnhx4zh33MEXlL0m1oV06zg3h8A==@kvack.org X-Gm-Message-State: AOJu0YxnucG283rdZSJknLPfuWkTlF0OT+OSVrQTucVMOhqhrWoSTYjF OvnS+d8fm0C+KZo96M+2nmks+55/2F/hCm1pROa5RYNLEiAUI7HXRW5QNC5YFxYlcDrssp3casx 5yWvwPS1kfg2qcWZ0I8W41jOnPKM= X-Gm-Gg: ASbGncu2J/UoFzQiJF8caKhEKtmVH0ApHXt45KJhoA1iwgTBONuRmS1OvrTqId4w+Zz eNduu6EritHVkm7Dr1tGW9WcTZSWPXWSq9NXrZj7F9b1X9vllPGas X-Google-Smtp-Source: AGHT+IFuUO/XUzFDgmBwcKMlS3No5xDuN3VafBZfvsaSSQwWP5CZu1NMytMAyWPDJAmFocUynNqsl5tuCyeMpjaZg+g= X-Received: by 2002:a05:6512:32c3:b0:542:2998:ac88 with SMTP id 2adb3069b0e04-5439c229121mr1860554e87.1.1737422941482; Mon, 20 Jan 2025 17:29:01 -0800 (PST) MIME-Version: 1.0 References: <20250120092604.3590285-1-zhaoyang.huang@unisoc.com> <625d91cc-59f3-4757-81df-220d32861493@nvidia.com> In-Reply-To: <625d91cc-59f3-4757-81df-220d32861493@nvidia.com> From: Zhaoyang Huang Date: Tue, 21 Jan 2025 09:28:49 +0800 X-Gm-Features: AbW1kvbAL2-AvPOTu8GdNf1YqD1gIdKRY2bwuToi19DCLymJjxmnL8WjJaAhuUo Message-ID: Subject: Re: [PATCH] mm: gup: fix infinite loop within __get_longterm_locked To: John Hubbard Cc: "zhaoyang.huang" , Andrew Morton , Alistair Popple , linux-mm@kvack.org, linux-kernel@vger.kernel.org, steve.kang@unisoc.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: AEE75A0004 X-Stat-Signature: ihxewnuhxdbif5yyr8b17ejt916eah4x X-HE-Tag: 1737422943-269069 X-HE-Meta: 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 ha7XgjWp r6GG0ZE2c151zyw4I+rdFO0eY2AK883si88sgPP4suP+faKXQeio8BPsm7SZksw+oqk4RNYiaboja0e1zFr7i0vt8uuzyZON567BJQuUqQruWByR17Pfzw0FI1VHmXvnDDLKLjnjdxmACNCMyq5uwvtFpU0aMzVvGzcBjX7DWEnCJ6Vcqqs8x3bBvZBglbqIzZ/Eb7GC2BtNIiE+nehOf7qwdMtAOAAlO4EXd6H91EGTKyx56wdH7pqf10sgkyQ1DB/PMaEpViwmCog89ipzQQH205d2ip+uMCwZQI8os+OUTD5S1uDkVxVxR9nkRFSjdY8TvE2F+YvPce/1sNN5MZvLsGsjCPIaMIHrXOxwRexUJ1SH1JsK0QfSTSEpq4xB2suqlN1FDIVMKFcgILAhTid2d92rKsNPq1iy3a5A5FWTier8GjA0LH9JVtYm/7ohD2l+W/1JAWkGVQn+VlbU2CkEdVT5AKO13DJk+SL2k1W5Dr7Y= X-Bogosity: Ham, tests=bogofilter, spamicity=0.001111, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jan 21, 2025 at 3:34=E2=80=AFAM John Hubbard = wrote: > > On 1/20/25 1:26 AM, zhaoyang.huang wrote: > > From: Zhaoyang Huang > > > > Infinite loop within __get_longterm_locked detected in an unique usage > > of pin_user_pages where the VA's pages are all unpinnable(vm_ops->fault > > function allocate pages via cma_alloc for hardware purpose and leave th= em > > out of LRU). Fixing this by have 'collected' reflect the actual number > > of pages in movable_folio_list. > > The above is rather terse, although perhaps by kernel standards it's OK. > > Isn't this missing a Fixes tag? > > Fixes: 67e139b02d994 ("mm/gup.c: refactor > check_and_migrate_movable_pages()") ok. will amend in v2 > > > > > Signed-off-by: Zhaoyang Huang > > --- > > mm/gup.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/mm/gup.c b/mm/gup.c > > index 3b75e631f369..2231ce7221f9 100644 > > --- a/mm/gup.c > > +++ b/mm/gup.c > > @@ -2341,8 +2341,6 @@ static unsigned long collect_longterm_unpinnable_= folios( > > if (folio_is_longterm_pinnable(folio)) > > continue; > > > > - collected++; > > - > > if (folio_is_device_coherent(folio)) > > continue; > > > > @@ -2359,6 +2357,8 @@ static unsigned long collect_longterm_unpinnable_= folios( > > if (!folio_isolate_lru(folio)) > > continue; > > > > + collected++; > > + > > Well, this seems correct to me. Somehow I talked myself into believing > that it was OK to do collected++ early, even though later on we skip > actually collecting the folio, thus miscounting things. > > But now I believe it was just incorrect all along. > > > Reviewed-by: John Hubbard thanks > > thanks, > -- > John Hubbard