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[67.164.59.41]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7b0cc17a956sm19641876b3a.44.2025.11.12.10.38.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Nov 2025 10:38:34 -0800 (PST) Date: Wed, 12 Nov 2025 10:38:32 -0800 From: "Vishal Moola (Oracle)" To: Uladzislau Rezki Cc: syzbot ci , akpm@linux-foundation.org, hch@lst.de, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzbot@lists.linux.dev, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot ci] Re: make vmalloc gfp flags usage more apparent Message-ID: References: <20251110160457.61791-1-vishal.moola@gmail.com> <69123b72.a70a0220.22f260.0105.GAE@google.com> Precedence: bulk X-Mailing-List: syzbot@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Nov 12, 2025 at 01:02:03PM +0100, Uladzislau Rezki wrote: > On Tue, Nov 11, 2025 at 11:07:29PM -0800, Christoph Hellwig wrote: > > On Tue, Nov 11, 2025 at 09:21:06PM +0100, Uladzislau Rezki wrote: > > > > Unexpected gfp: 0x100000 (__GFP_HARDWALL). Fixing up to gfp: 0xdc0 (GFP_KERNEL|__GFP_ZERO). Fix your code! > > > > > > > It looks like we need to add __GFP_HARDWALL to the white-list-mask. > > > > __GFP_HARDWALL is part of GFP_USER. Doing GFP_USER vmalloc sounds like > > a bit of an odd idea to me, but there are a few users mostly in bpf > > and drm code (why do these always show up for odd API usage patterns?). > > > > So I guess yes, we'll need to allow it for now, but I'd like to start > > a discussion if it really makes much sense. > > > > /* plain bpf_prog allocation */ > prog = bpf_prog_alloc(bpf_prog_size(attr->insn_cnt), GFP_USER); > if (!prog) { > > > I assume that was the place that triggered the splat. > > Vishal, will you send the patch adding GFP_USER to address the splat? Yes, I'll send a new version including __GFP_HARDWALL in the mask and update the comment accordingly.