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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qP69s-007mZw-6K; Thu, 27 Jul 2023 18:56:20 +0000 Date: Thu, 27 Jul 2023 19:56:20 +0100 From: Matthew Wilcox To: syzbot Cc: akpm@linux-foundation.org, liam.howlett@oracle.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [mm?] WARNING: suspicious RCU usage in mas_walk (2) Message-ID: References: <000000000000607ff905ffc8e477@google.com> <0000000000000aeb7f06015e5cbd@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0000000000000aeb7f06015e5cbd@google.com> X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 8D2C418001F X-Stat-Signature: fndbote9mk77qdnbcdq34a9ekmnfmxcx X-HE-Tag: 1690484185-919927 X-HE-Meta: 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 4GcGRpRE XSleDAWyIFHpQWoVJWePu4SH3GarstJ52wmruPjp0TnAs0mV2+G/Ubep0ZvsmvlYhXx+uWOW9ovlFBTtwzO61DDpizEbV8Ge3bLSf8xamyUecZ1cS3vc6ql16ExVL4JGB+pDNJelW8Bb2NrT375udbNETTmXYDvhKzOF4iZQehBi4EBwb/2ZM6JfIII+dUplhkDUpO2cK6ZWU9+k5E8eoeiaUOrIZtCKOCB9va/peVGvqxTMtHV1EnItdZL7xWc6/ZVgq1TQxhSG5KOvJc3KbSLidluc1IpPpSkM/6peocP6ikkGaldRcumwqY/ttGzX2WnM6IlTeQT5D3LxRX7002ITI827TVxihS20klrw1kOrYPpkbgghNpBRQACt6vxECrngloOY+UBwAQ7+SkU+Oxv9DN3wY/Laa6nJck7eWwaruf9BqwPTHrWDFc+LnCoEGDPSUxDGKQw6RCWQLSKWYXFXqADs92MH5BKuIPhtXnfoonPn82AFYSNlrkgkla99PseAoWVHEn5vL7G+r8MMdVGv7dQ== 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: On Tue, Jul 25, 2023 at 11:57:22PM -0700, syzbot wrote: > syzbot has bisected this issue to: > > commit a52f58b34afe095ebc5823684eb264404dad6f7b > Author: Matthew Wilcox (Oracle) > Date: Mon Jul 24 18:54:10 2023 +0000 > > mm: handle faults that merely update the accessed bit under the VMA lock > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1783585ea80000 > start commit: [unknown] > git tree: linux-next #syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next next-20230727 diff --git a/mm/memory.c b/mm/memory.c index 20a2e9ed4aeb..57b271108bdc 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3567,6 +3567,12 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf) return 0; } copy: + if ((vmf->flags & FAULT_FLAG_VMA_LOCK) && !vma->anon_vma) { + pte_unmap_unlock(vmf->pte, vmf->ptl); + vma_end_read(vmf->vma); + return VM_FAULT_RETRY; + } + /* * Ok, we need to copy. Oh, well.. */