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AJvYcCUaBQeFCOrzBc63Ts1cTRI35O9kkQRZ1jjBc+zUoKHc8x3HKoE8W3i+4Ku7Rn8cvu2HhOTbARy6Sw==@kvack.org X-Gm-Message-State: AOJu0Yyq3sFH5DgHRCL8rdrHVUv7P5+Wat9uC7Lp8r37/uiAOEEL9HLQ 6beXcFuOkxfRSj8PzxoBNYEGdn4yZ/QtETUDlqTU2QatPBzCTM+rpYZsjewV555TPqWkf6qe0yS zs01hPx72Y8hEf9pHUzG5c5QSluM= X-Google-Smtp-Source: AGHT+IEoWVV3J28AqNRDaa8EBZcliKYPTohZN2yjyXFkS57mLRYybPWak3Y1DW9pUeNIspX/56oBRC6mnhVfXdPs3oc= X-Received: by 2002:a05:6358:9986:b0:1b3:93b8:8c1e with SMTP id e5c5f4694b2df-1b603bebef8mr2994418355d.2.1725594635203; Thu, 05 Sep 2024 20:50:35 -0700 (PDT) MIME-Version: 1.0 References: <20240905095216.7888-1-wangyibo@uniontech.com> <50595531-87b0-4420-9624-948810066a6e@redhat.com> In-Reply-To: <50595531-87b0-4420-9624-948810066a6e@redhat.com> From: Lucien Wang Date: Fri, 6 Sep 2024 11:50:23 +0800 Message-ID: Subject: Re: [PATCH] mm: move bad zone checking before getting it To: David Hildenbrand Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, trivial@kernel.org, Wang Yibo Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: op1cooi6mmwdrwodtthbj5t87pi7fqjb X-Rspamd-Queue-Id: 579211C0009 X-Rspamd-Server: rspam02 X-HE-Tag: 1725594636-391065 X-HE-Meta: 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 cFZPa5u5 Z1rOErVEhf8c1FJaiFxP0AijNIBKEvV8PDeCnpXt51BwUdk1pGOxitmCZ3Fq3+hZUft4wdnYy+e421s7z2UTX3RJtD67/7yg4SDG5PpTRZDQO3Dc80r8Z8hZNiSVBhE2zTdU+pb6maKts3uERc7BCDmRlc8eoEKEaCbMCBUwrJtWg/B3WLXdPSlsuH4Eh8UoDKcd29cofMz1S+QL/ss108UrRDqSaTHbTeO2lPwbsiojun9YdSzK9Jmv7NFFOLaqHOPyRSw3PPbghaJGTab14fXld6wkMN+gf9159UD6KpCZ+VuambBdsWqVQjS2MX46wjNbTKj7PlpsT9bw66bZOH9kK1rJb6jzgQztdObNA2Hdpfa57+WNQQmGyCqnrs0zRICPUG35+c+gWimb8omnNUCUmww== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, 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 Thu, Sep 5, 2024 at 6:22=E2=80=AFPM David Hildenbrand = wrote: > > On 05.09.24 11:52, Wang Yibo wrote: > > When flags from gfp_zone() has an error combination, VM_BUG_ON() should= firt know it before use it. > > s/firt/first/ > > Please break long lines. (checkpatch.pl should have warned you) I will change it. > > > > > Signed-off-by: Wang Yibo > > --- > > include/linux/gfp.h | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > > index f53f76e0b17e..ca61b2440ab3 100644 > > --- a/include/linux/gfp.h > > +++ b/include/linux/gfp.h > > @@ -133,10 +133,11 @@ static inline enum zone_type gfp_zone(gfp_t flags= ) > > { > > enum zone_type z; > > int bit =3D (__force int) (flags & GFP_ZONEMASK); > > + VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); > > Better use VM_WARN_ON_ONCE() instead while at it. Although I do not know what results BAD ZONE flags combinations will cause, I think maybe a BUG is necessary for security ? > > > > > z =3D (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) & > > ((1 << GFP_ZONES_SHIFT) - 1); > > - VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); > > + > > Unrelated whitespace change. I will change it. > > > return z; > > } > > > > But I don't see why we would want this change? It's not like the kernel > would crash when calculating z. > > Or is there some change in behavior I am missing? I just think flags checking should precede using it logically, when I review these partial codes. So I submit this patch, there is no other reason. > > -- > Cheers, > > David / dhildenb >