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b=qpH2E1M0hDRVkWkc6HN5OsZ9LRQwvROi0pn480R2jtbJxRw81caSggF/cYn5KvR3a 5M6NSMttg14QwG2/q7q7ffOAwTpfzKGDR5GHFWSfMV1aBBCNQSga9vp8VjBz3D6O+w RZLocMg+8pQi0GmbM2RveVjonvaBypwSUzeKBbF6tljvr1XljrBKe4vAjnDugsW1zK ss1I/JDGG+AB/gfWBcwX+6f3GOgQSUmGrhA+M2jvYuLBVF96NAWGXye9ZoMmXe3L15 eo/NV70c8CU60gh13KVCR9YtEbSIzigsKRJEIGnCfj21L2qaJ7dzBR5sz2/XjcR1bn HNn8L3TqPu6Mg== Date: Thu, 19 Mar 2026 07:45:53 +0200 From: Mike Rapoport To: "Lorenzo Stoakes (Oracle)" Cc: syzbot , Liam.Howlett@oracle.com, akpm@linux-foundation.org, baohua@kernel.org, baolin.wang@linux.alibaba.com, david@kernel.org, dev.jain@arm.com, lance.yang@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, npache@redhat.com, ryan.roberts@arm.com, syzkaller-bugs@googlegroups.com, ziy@nvidia.com, Harry Yoo Subject: Re: [syzbot] [mm?] general protection fault in zap_huge_pmd Message-ID: References: <69babeba.050a0220.1b2d94.0003.GAE@google.com> <6b3d7ad7-49e1-407a-903d-3103704160d8@lucifer.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6b3d7ad7-49e1-407a-903d-3103704160d8@lucifer.local> X-Stat-Signature: znga99hd1jzfxj7psrk8x1b5e4o9fydn X-Rspam-User: X-Rspamd-Queue-Id: E9FCD1C0005 X-Rspamd-Server: rspam12 X-HE-Tag: 1773899163-231056 X-HE-Meta: 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 +YS9n17L 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Mar 18, 2026 at 05:26:32PM +0000, Lorenzo Stoakes (Oracle) wrote: > +cc Mike for uffd, Harry for fix that also resolves this, see below > > On Wed, Mar 18, 2026 at 08:03:22AM -0700, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: b84a0ebe421c Add linux-next specific files for 20260313 > > For some reason I have to git pull --tags to get this... commit hash locally? > Strange. > > > git tree: linux-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=119ddd52580000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=e7280ad1f68b2dce > > dashboard link: https://syzkaller.appspot.com/bug?extid=de14f7701c22477db718 > > compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=173b44da580000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1537b8da580000 > > @SYZKALLER guys: > > Note: the repro is incorrectly labelling; > > // ioctl$UFFDIO_CONTINUE arguments: [ > // fd: fd_uffd (resource) > // cmd: const = 0xc020aa08 (4 bytes) > > as UFFDIO_CONTINUE (0x7), it's actually UFFDIO_POISION (0x8) as you can see > from least-significant byte. > > It's also stating things like mmap flags wrong e.g.: > > /*flags=MAP_UNINITIALIZED|MAP_POPULATE|MAP_NORESERVE|MAP_NONBLOCK|MAP_HUGETLB|0x8c4b815a506002b2*/ > 0x8c4b815a5465c2b2ul, As Andrey Vagin pointed off-list, you can run strace repro and see the syscall arguments quite nicely :-) > So Harry's fix resolves this, and that's the important bit ;-P > but we should handle this case better in zap_huge_pmd(), I will send a > patch for that. > Cheers, Lorenzo -- Sincerely yours, Mike.