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b=LLFZVYwdRQRn5LS9+rcV07qD/UHANjm3rQURxV/A/h0lUkTiFrAtI7nDn5foYS6N+ G4b1u2kDHw7TxZBpfFPVF7rmbjCozhcGY4gOt/NzJg2/CsIJLvl8kdmEC5KSJBNe/t Ei/y6LWzSC6gpJ+oV3eof8Vh8mAM8+pAQE3TAGQ7QizjWjyVwwd9ts3mHTwXweSbMT lyjsYBvZPf0gcpmEaWtcvgQ/7gtbYAHWh4tRPSlYaQr4VmgI3HeMRnfQuzff7FrmBK krSmSqQvGfzxyX8ofsI/zCaJfnXzChUltPqDagN4lT+/vew6Fi0rRXs3n64Kd2ZZ9e SYrcg/dQtuotA== From: SeongJae Park To: "Lorenzo Stoakes (Oracle)" Cc: SeongJae Park , Andrew Morton , Johannes Weiner , Yosry Ahmed , Nhat Pham , Chengming Zhou , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH mm-hotfixes] mm/zswap: add missing kunmap_local() Date: Mon, 16 Mar 2026 17:38:02 -0700 Message-ID: <20260317003803.89459-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260316140122.339697-1-ljs@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: E441118000E X-Stat-Signature: nx1o411sckdddeejpd7aojxmfjrhud9w X-HE-Tag: 1773707890-663707 X-HE-Meta: U2FsdGVkX1+K03PDSkvjsx5EHdyLjPqx+xk3OUb5JumTZ1kKZf8L+ByEyzBK+dg3jLwFKtDWzzIqnzuVwhN4CPsM0+DR+93VK3uXNAr5+3234gSUIu+UupCO5ZhpJrNevQ5CrrQirIIM//2vfrAY/BatB+TDk8k9o27B+wiWeSYHxt4EgNGSJlA2eJKEANERJZYsf1HBZvjF5zETxSTLk/yKzbG5+otohuPMx2JZgE//ZXjPB+6mHd7RQWvjdeNlCNy8mR6mE2hvI4n4hLq29g78K7LRBaGuWmeMqc/fJ3JxSxiYlkICtqe0SCN0oRH/KNTMPOQ/t1CVnniDVeOm38dKlvx9UeQhVVak0wG5sVqtOWAWpr61NTAIW0YuxaOQ334cflge4lAzisa/t8wENsSp6YvyMtmWD2iM/9weqjHTpyydB2cayrMKe8UmB2rxdLCNT44yx5GLaa45S4a/XjnSasJO1vJLasNKiEPA0/o2qpueFOzuAE1Ugadqguw/dIPEK9DRyyfy+tpA7OXsNuQziGvHlPIXqkpIaoSwF1/rYnkVMGNS2kxAPELmvTUIAoCSOoBfPP/WE6gfwPeuFpuE9rmyLkhhSGJVjmgePGtjubFFUeFRvsyod06zyc+iji5rZrq61SzNpVSQGsRtxYQO+iKaRHEKnEUhh5o2ph8J48XJ69ilGFNPk6F795xG79M4+2aaBLC4zYmzq8Bm/9sSH6sRNKaNYqpZ2QAFiGuEv1gJzdIgGH0gYOhfDC54to2lX8WnD/kxvo/2NnfW6MsRV1BpfnyP/BQQhxUqmihYYv91XlUyXCC1doGA1R0l+eT4tNH3iOytGa6QsTApZcMM8QSptWkjHUhxXZJV9hk5QhC6wL8YDkFtrVz2+1xu0jjfo/tihcuLnd24Pp/HveksNvvbjyFo481y2oEePp4+d2ApKIGUqShkIxWUn9eUi7Ya+9XRYxIsFT5DA1I aS55LkKb YlllUxg4+WJ6Pc2iB+dYUYCLPTu3r/jAfoHfK3LOJrT7y7LK+zhaxgonQGLEWo2R0a47Yu0ZDfmjATAVk4wAlQaXkXowvDJyE0KSLBlJ4g56m1aYehSr8f+A44DoeRu7IhimwGCP3JjZULzlwvqau+NmAMj2kuH56dgaQY4xw29/l27U0iVc6MoufptSnO6un6JmfIwBFRfTpuq8faoC6ZaU0GI/dY0KCLfi4gzGYlmruTqt/yDu9RCEFsmpokD/uDAmDJAAsVtB2QX3FG7Q5lV0b6K8RAsmBwqLMBkMsQQtP9x6IBblglzkHGZHFhsuZ6i1LFQ9AkeE7C/HaMMQwVJ5FpK+T+AjIZE7e9A7eprk5JJU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 16 Mar 2026 14:01:22 +0000 "Lorenzo Stoakes (Oracle)" wrote: > Commit e2c3b6b21c77 ("mm: zswap: use SG list decompression APIs from > zsmalloc") updated zswap_decompress() to use the scatterwalk API to copy > data for uncompressed pages. > > In doing so, it mapped kernel memory locally for 32-bit kernels using > kmap_local_folio(), however it never unmapped this memory. > > This resulted in the linked syzbot report where a BUG_ON() is triggered due > to leaking the kmap slot. > > This patch fixes the issue by explicitly unmapping the established kmap. Nice catch, thank you for this fix! > > Reported-by: syzbot+fe426bef95363177631d@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/69b75e2c.050a0220.12d28.015a.GAE@google.com > Fixes: e2c3b6b21c77 ("mm: zswap: use SG list decompression APIs from zsmalloc") > Signed-off-by: Lorenzo Stoakes (Oracle) Reviewed-by: SeongJae Park Thanks, SJ [...]