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Received: from viro by zeniv.linux.org.uk with local (Exim 4.96 #2 (Red Hat Linux)) id 1rVkYP-003dd3-0Z; Fri, 02 Feb 2024 03:49:25 +0000 Date: Fri, 2 Feb 2024 03:49:25 +0000 From: Al Viro To: Doug Anderson Cc: Christian Brauner , Eric Biederman , Jan Kara , Kees Cook , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] regset: use vmalloc() for regset_get_alloc() Message-ID: <20240202034925.GW2087318@ZenIV> References: <20240201171159.1.Id9ad163b60d21c9e56c2d686b0cc9083a8ba7924@changeid> <20240202012249.GU2087318@ZenIV> <20240202030438.GV2087318@ZenIV> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 52ED64000C X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: e5m57bftp4fiyyms4oir7q8ehxzz9jq1 X-HE-Tag: 1706845778-294861 X-HE-Meta: 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 NsMuSzeo 5dt8NGBRpeP8uGpKYMZkdMvzUGtlFiw51JQe/ydiLhE0/iJOQ8csMgA9ZIY1KLo98O8HNtWRFs9Tg1wwvNCIyoYlK1LoZnjbU+GyKbUCBjN6yAqoWWexXVDej5qHFoh3sZ9W5QcylZJSz/XbhKMr58Ew0XMUZ1nKUrbpnfPl886CUPvVP4CVgvyGSQ49wDLX/mBidsBK+o1LHL1gi0+ecLWczTZrN6NogzxDPJQ++3vVOClwXeVcSeFxU1Ad39qFH7rUbFOIB76w+rf1G8M3pKpZaxgiUJAtgElI1uTia+3rCleYw+PEtoc/OppV1kc0fZipEJ29phWAw9BYdGbTWpomqSOGjlEuNMnCMVrbDurd24sEIhNhlv+/KNPlkRj46ajEXoGYsP+pOFGs= 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, Feb 01, 2024 at 07:15:48PM -0800, Doug Anderson wrote: > > > > Well, the next step would be to see which regset it is - if you > > see that kind of allocation, print regset->n, regset->size and > > regset->core_note_type. > > Of course! Here are the big ones: > > [ 45.875574] DOUG: Allocating 279584 bytes, n=17474, size=16, > core_note_type=1029 0x405, NT_ARM_SVE [REGSET_SVE] = { /* Scalable Vector Extension */ .core_note_type = NT_ARM_SVE, .n = DIV_ROUND_UP(SVE_PT_SIZE(SVE_VQ_MAX, SVE_PT_REGS_SVE), SVE_VQ_BYTES), .size = SVE_VQ_BYTES, IDGI. Wasn't SVE up to 32 * 2Kbit, i.e. 8Kbyte max? Any ARM folks around? Sure, I understand that it's variable-sized and we want to allocate enough for the worst case, but can we really get about 280Kb there? Context switches would be really unpleasant on such boxen... > [ 45.884809] DOUG: Allocating 8768 bytes, n=548, size=16, core_note_type=1035 > [ 45.893958] DOUG: Allocating 65552 bytes, n=4097, size=16, > core_note_type=1036 0x40c, NT_ARM_ZA. /* * ZA is a single register but it's variably sized and * the ptrace core requires that the size of any data * be an exact multiple of the configured register * size so report as though we had SVE_VQ_BYTES * registers. These values aren't exposed to * userspace. */ .n = DIV_ROUND_UP(ZA_PT_SIZE(SME_VQ_MAX), SVE_VQ_BYTES), .size = SVE_VQ_BYTES,