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AJvYcCWLvNj+HSnX+XiJysysHHVG2eg8t2LibTbBVLIYYZkuHcKktNSETldBYafREhc5abFR+DiguSOb3A==@kvack.org X-Gm-Message-State: AOJu0Yyqzdr9WDEdSWUY/VJdJxErX0a7MW4oNUa4S4YPJ8uOLMGBGJCf I4jkhOMXxf6bEdtc+isBmrcHwmdquK2C8skFRtEbFMqRMOJY+hP6zK2QayxX7sD1/nnpqQsf+0M +QwpBMHRVO6T98BcS22BJaIIDSiSiLJvj+VwfibGy X-Gm-Gg: ASbGncuNT/Wj+6qze8sN4+7RDr+OEstvSwSjMtaG2DYZZ2Nub+6UPuqJisRL8Oi9XBX AAhtiVW4Rtfz+LyTFO/qFZtY96Tlck5ROxyINuQjBCgleLmqjlNQHFYhOHbQA2SAmcsIsWq+Xaw rn1mEBKqdNlgZppO7B64AYsoYPS/PToknKBX0gehiK5JyQgnF3yfqEDZNlyJzzlURjkzCz2jpWL vgHCY9EuABaNDLeG/oS1MZ92UFvPCRQPICJ6rXgi+PR X-Google-Smtp-Source: AGHT+IFwYG+oXNRCy8GEbBjKw5plhsNBK2EMVusWy6/CWD8cxMIvggWuNYsOlNkHxqipGFQAF+JfnH7EHJbUsSVWNCs= X-Received: by 2002:ac8:7f04:0:b0:4b3:509b:8031 with SMTP id d75a77b69052e-4b626ecdc80mr14570821cf.13.1757621542016; Thu, 11 Sep 2025 13:12:22 -0700 (PDT) MIME-Version: 1.0 References: <20250909233409.1013367-1-surenb@google.com> <20250909233409.1013367-4-surenb@google.com> In-Reply-To: From: Suren Baghdasaryan Date: Thu, 11 Sep 2025 13:12:11 -0700 X-Gm-Features: AS18NWAsvUZp8hHhTH4zlA907OSikwteEZk4N0sF9oy4TY-FkBF6EehF-T2LNl0 Message-ID: Subject: Re: [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages To: Shakeel Butt Cc: akpm@linux-foundation.org, kent.overstreet@linux.dev, vbabka@suse.cz, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, usamaarif642@gmail.com, 00107082@163.com, pasha.tatashin@soleen.com, souravpanda@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 88D221C0009 X-Stat-Signature: uo6xzoomo8tq595uqpu1gsskkji67ssr X-Rspam-User: X-HE-Tag: 1757621543-521682 X-HE-Meta: U2FsdGVkX18UPnBLnVcuyg+S60ScgPqNJU4z3zJxbVup7O8HOPQXCRbYGA5q5aY8FzMMjHYLYlZqDZFDAJ/kpA8fT9QgW4GjsB60XXAbLLnHVMVs482R8WogvpG8R74FugVsq8LL2Lg8JuiCiku5iJYmNXLPyaSkAtL+n9zuVFcbI/DJlA514oG1cFh9TjD2IT6c7kPo2AReTjrkVULx57KAK2lUFF/czedT9ie2Z/74yk4dsrnr8jvRMSt6r99dwxCBX/2p699v8lVVXNk58gU1AY5/afDWBJdPC/aOzqZ+3CRD5JJaVhCzjKcbkTdMC2R2gKOo+Ih2o3N8vfWyoQkGgGnPXLZtNE7lExkhhnmTrvxfnPiW2QmKmguyBDESz14ulknxgR1X5Fmtvx5XhoP86FzZd/DzCh3Vxzgxd480fq64P0tfW0HP4IYydGmetoQ3aXV76nU3kfMw5D4IyzjlugSaCBh6uGYuqpUntVlUyyVywHuHMzDzel/vptygWR4vb2QagvvjKzXIaxK0HrQ1bo/GOdHz7LHpONO3fcBlu7VLCg7oave3E4sraJVMFuqqi3Gt7kS652tvsR5JuYjE859CdPPElNz1suyNjY9O3VkgGoM5t3S1NxEHlul861sssI7cbCDBb5kH6M6KedmJSmySOI519ktjpIQp8NknPKT4ugGHVPcCxBdRQhz43KO3RuYm7bQ5RXtvJHXDln1T4NMxUjM87kLPprP+xnf4cWugqvyRqDyAf4dqmUrvI2jFBqG3JQ7Gn25XzrnIPukPIVCgzTYGCBEhK2/ce7gBxc5RvDF6QeJMmJ6cXn4Pmbxc97/RWEUvPN0EGsWBlz1OpguhYM3DhVvTP4VeGU8nWxHnKGYjp+MxBsNYfY7awjRgc2BDVe1kNLx1PLkTp532kboZ0T9ANMp1N5a2uHk41wDQZniwY8Bh80zfjd+keICMlGL9lQLD+G/LMSy 2B+hmrpW R3WC0ynv5d1I7NFTkotHLOZ0cAWNlBoNFwS83j6+24zc0GWMVbhMX3bI+lZ2xzxjVukmdQUGkNc/wvGVQiQWFLi/NTP5jsZLvLqeaqofGbLtv95Obh1ApIFM2Y0HLzwVITZHGhz0h8ZRYw3Eacr/C81RZMpZuka/PMcA5ZEcr1W0K9dMp9Tt1xXc+eSkSBH607sbz/BeicTrrR0DMjaG5cScpAekAmlvvqhspQqC/vRaqMGRkJQJpxblXT1p4LjVQZ1PnI4KQJ4Qxenuo5j1mIvINK28x+JHoUq2XAl8siPilADmtsXBdzf58mw== 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 11, 2025 at 1:01=E2=80=AFPM Shakeel Butt wrote: > > On Tue, Sep 09, 2025 at 04:34:09PM -0700, Suren Baghdasaryan wrote: > > When freeing "tail" pages of a non-compount high-order page, we properl= y > > subtract the allocation tag counters, however later when these pages ar= e > > released, alloc_tag_sub() will issue warnings because tags for these pa= ges > > are NULL. > > This issue was originally anticipated by Vlastimil in his review [1] an= d > > then recently reported by David. > > Prevent warnings by marking the tags empty. > > > > [1] https://lore.kernel.org/all/6db0f0c8-81cb-4d04-9560-ba73d63db4b8@su= se.cz/ > > > > Suggested-by: David Wang <00107082@163.com> > > Signed-off-by: Suren Baghdasaryan > > --- > > mm/page_alloc.c | 9 ++++++++- > > 1 file changed, 8 insertions(+), 1 deletion(-) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 1760346bbd24..d21a411e807e 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -5240,9 +5240,16 @@ static void ___free_pages(struct page *page, uns= igned int order, > > __free_frozen_pages(page, order, fpi_flags); > > else if (!head) { > > pgalloc_tag_sub_pages(tag, (1 << order) - 1); > > - while (order-- > 0) > > + while (order-- > 0) { > > + /* > > + * The "tail" pages of this non-compound high-ord= er > > + * page will have no code tags, so to avoid warni= ngs > > + * mark them as empty. > > + */ > > + clear_page_tag_ref(page + (1 << order)); > > Do we need something similar for the release_pages() code path or is it > happening already? Pages released with release_pages() should have valid tags, so I expect no warnings. > > > __free_frozen_pages(page + (1 << order), order, > > fpi_flags); > > + } > > } > > } > > > > -- > > 2.51.0.384.g4c02a37b29-goog > > >