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AJvYcCUzy952UYV8DCLnVwNLKzOW7fOVcv+b1Y+XLDcR1eKtnYOpx0tfv2DeIC8r8SHxs5hEpo0KRnZTy3kgGLLH6b5EMRE= X-Gm-Message-State: AOJu0Yx8qBb/Yh1Vn/0rq9HNYmtyFRw9pA54EwqbLF9sMfJkOY8BzyB/ YdfiDzkKyV977022UO8XQxuxE3no9ydo1BHtmdbX84ijcRifnUrfK4XAHNxubTxg+rluMQ8mgsG AmFDkbbWt5vuwH3kTJV8GcPZpM7sNGMSexB4O X-Google-Smtp-Source: AGHT+IG2Ylwf4qP53KT8n9LuQFgtOaFeplGVLRIskw5ThK8EM33Q7t3846sahBbOoJlS7aJZoeVlMm+NykS0UDg32fQ= X-Received: by 2002:a05:6512:1cd:b0:52c:859c:91dd with SMTP id 2adb3069b0e04-52ce18327aamr3287502e87.5.1719255272205; Mon, 24 Jun 2024 11:54:32 -0700 (PDT) MIME-Version: 1.0 References: <202406241651.963e3e78-oliver.sang@intel.com> In-Reply-To: From: Yosry Ahmed Date: Mon, 24 Jun 2024 11:53:55 -0700 Message-ID: Subject: Re: [linux-next:master] [mm] 0fa2857d23: WARNING:at_mm/page_alloc.c:#__alloc_pages_noprof To: Usama Arif Cc: Matthew Wilcox , kernel test robot , oe-lkp@lists.linux.dev, lkp@intel.com, Linux Memory Management List , Andrew Morton , Chengming Zhou , Nhat Pham , David Hildenbrand , "Huang, Ying" , Hugh Dickins , Johannes Weiner , Shakeel Butt , Andi Kleen , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 506651C0013 X-Stat-Signature: zfm75ic7p9eew4qp1ucqnpagaptimjy3 X-HE-Tag: 1719255274-304814 X-HE-Meta: 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 QIcFqTWn Eox92OpXAnsKaWVYonXGU37bEII+xkZw5FPzZsiCxknr4rXXCtHgvD5MmzhzCpdyIkzJENY+CJo9/CFgiflvmBgsDDO/E2Yg2JjBlXnGSuhppiEfeTZLe4nWSCeErYrxZMSjLeqk/JfqBOCNUORIEsEJAFw6KQ0o1WM5EllMMh7giJ6+/QB07On5js93VHlpfjNNw5Zd3hLupE2SEt/7vGsJFuPkCRnn2o+ksQoI1AV+ZT14DUav6bwxPQjThLHhg97G4gaP00RkW93r65umcPimTvbVhRykUqfJv2SF3OQ1l8vAKfxxdIT1iij8M/VKODSnl 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 Mon, Jun 24, 2024 at 11:50=E2=80=AFAM Usama Arif wrote: > > > On 24/06/2024 21:33, Matthew Wilcox wrote: > > On Mon, Jun 24, 2024 at 05:05:56AM -0700, Yosry Ahmed wrote: > >> On Mon, Jun 24, 2024 at 1:49=E2=80=AFAM kernel test robot wrote: > >>> kernel test robot noticed "WARNING:at_mm/page_alloc.c:#__alloc_pages_= noprof" on: > >>> > >>> commit: 0fa2857d23aa170e5e28d13c467b303b0065aad8 ("mm: store zero pag= es to be swapped out in a bitmap") > >>> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git mast= er > >> This is coming from WARN_ON_ONCE_GFP(order > MAX_PAGE_ORDER, gfp), and > >> is triggered by the new bitmap_zalloc() call in the swapon path. For a > >> sufficiently large swapfile, bitmap_zalloc() (which uses kmalloc() > >> under the hood) cannot be used to allocate the bitmap. > > Do we need to use a bitmap? > > > > We could place a special entry in the swapcache instead (there's > > XA_ZERO_ENTRY already defined, and if we need a different entry that's > > not XA_ZERO_ENTRY, there's room for a few hundred more special entries)= . > > I was going for the most space-efficient and simplest data structure, > which is bitmap. I believe xarray is either pointer or integer between 0 > and LONG_MAX? We could convert the individual bits into integer and > store them, and have another function to extract the integer stored in > xarray to a bit, but I think thats basically a separate bitmap_xarray > API (which would probably take more space than a traditional bitmap API, > and I dont want to make this series dependent on something like that), > so I would prefer to use bitmap. I believe Matthew meant reusing the xarray used by the existing swapcache, not adding a new one for this purpose. See my response.