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Received: from viro by zeniv.linux.org.uk with local (Exim 4.99 #2 (Red Hat Linux)) id 1vTwfa-0000000BlXc-1NdW; Fri, 12 Dec 2025 06:30:26 +0000 Date: Fri, 12 Dec 2025 06:30:26 +0000 From: Al Viro To: Hugh Dickins Cc: Christian Brauner , Andrew Morton , Baolin Wang , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: 6.19 tmpfs __d_lookup() lockup Message-ID: <20251212063026.GF1712166@ZenIV> References: <47e9d03c-7a50-2c7d-247d-36f95a5329ed@google.com> <20251212050225.GD1712166@ZenIV> <20251212053452.GE1712166@ZenIV> <8ab63110-38b2-2188-91c5-909addfc9b23@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8ab63110-38b2-2188-91c5-909addfc9b23@google.com> X-Rspam-User: X-Rspamd-Queue-Id: 07DD6100013 X-Rspamd-Server: rspam04 X-Stat-Signature: 6tws8etihuwnn7thosbpo68fybjj6z8i X-HE-Tag: 1765521000-467004 X-HE-Meta: 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 Ml7jMjwL XTa/iqNEwgHJIi1mEwVxTWEvZ7CIt2LNTaj0XyQJAvo1Kk83QhUSU4EEgliOqvoe+8bL6Iw3yK8yGOG0BKpgTjdZK1ciHRvATMeQZfa0Jo5+tzqzcuXptQpJKYnQ5avdX/6sMZ0XbWiXDPro7zIqBQlT107PVg9cAvzQonnExySVy7n+COFfTkFuzeWNLALPuLNZNJFx5EK/60z+HGlYdwefY8Y5oBrj9n95E/6ya/MGE48c2u35LvnrYSaPfTrovP3CADpuwwN2c6Grk4KLFh3xeVN3WgyniWSednIz4UmpgcOLt4PK9D9trCr9rbRWH+5GnMPbOM63fIJtGnWhDSHCOSrhQDDZWS8/uyWgXRKAkeyUzPQxdQZlWRRD950DbMWRzcb/KwAlMFeN4JhvbunymaL0LCwD8PDdK7E5dGhAZg77DR5pmtWbTrIMTNH9DIz5rgkRnkqdvz/eATBJrkohM+TCIn1NbTyaRbs+5QkeQiqk= 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, Dec 11, 2025 at 09:57:15PM -0800, Hugh Dickins wrote: > No, sad to say, CONFIG_UNICODE is not set. > > (I see why you're asking, I did notice from the diff that the > case-folding stuff in shmem.c used to do something different but > now the same in several places; but the case-folding people will > have to look out for themselves, it's beyond me.) > > (And yes, I was being stupid in my previous response: once I looked > at how simple d_in_lookup() is, I understood your "hitting"; but at > least I gave the right answer, no, that warning does not show up.) A few more things to check: 1) do we, by any chance, ever see dentry_free() called with dentry->d_flags & DCACHE_PERSISTENT? 2) does d_make_persistent() ever call __d_rehash() when called with dentry->d_sb->s_magic == TMPFS_MAGIC? 3) is shmem_whiteout() ever called? If that's the case, could you try to remove that d_rehash() call in it and see what happens? Because that's another place where shmem is playing odd games...