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b=KKR4hC0hisUM68EidQUezR8zfwNy0414zRBBLqO65Nl+SsArL+flSO5eWsVfIE24o AfQQNHa8nvQ8Ri2p8ghrcZ86orQfPeVsaquEYI1xm2CjqTrS20K4EaLnyLcsjs25Si ZQw1C7ANRR92SQPXctO2KqWJn8WCnWNLp77U3sUr18v36L1X6JvXKboeYtNJ1IPo6h caQ8FAjONcV87XXUOa1zCIiGRQpzpxm/uEb1aiRQ95h1HEb+tC9YrFxX5QOHKApn44 gEuifJKyeNAmxwe2LQJcCo+KD7XF5DbGRKwao4yLlKXTDPVm37hmehQpfQbgtEoyfo +DGmTfWAh/G3w== From: Pratyush Yadav To: Mike Rapoport Cc: Pratyush Yadav , Pasha Tatashin , Alexander Graf , Muchun Song , Oscar Salvador , David Hildenbrand , Andrew Morton , Jason Miu , Jork Loeser , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 18/22] kho: extend scratch In-Reply-To: <178540063445.2151126.14089645580528118019.b4-review@b4> (Mike Rapoport's message of "Thu, 30 Jul 2026 11:37:14 +0300") References: <20260729145610.2827231-1-pratyush@kernel.org> <20260729145610.2827231-19-pratyush@kernel.org> <178540063445.2151126.14089645580528118019.b4-review@b4> Date: Thu, 30 Jul 2026 13:48:36 +0200 Message-ID: <2vxzqzkk7l63.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 9540A20004 X-Rspam-User: X-Stat-Signature: mckyhxi6erk6jzotaigk6ofgmbi3dyqb X-HE-Tag: 1785412120-436226 X-HE-Meta: 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 CypSUKnq yxHTI4gIWclHs98/MK51b/TXc5+ZB1ScCA4oosCIzT7KNfJMatHwLdxOV5K4BsXFFIecuBKSpZTnVLw8V+3EYkHWsR4/Fng9QWF1qWFhcJfqpBSHZTTGDWxrFzSQcc51pybpz5yGV46szWS3n9jomow9eGHVNO1yL/IDJ1WFX69w7M2fL5ffGuprAZXDEaqd0qHMAwFoZ3QDH4ZXXDHPqO28vUQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jul 30 2026, Mike Rapoport wrote: >> +static void __init kho_extend_scratch(void) >> +{ >> + const struct kho_radix_walk_cb kho_cb = { >> + .leaf = kho_ext_walk_leaf, >> + .node = kho_ext_walk_node, >> + }; >> + const struct kho_radix_walk_cb ext_cb = { >> + .leaf = kho_ext_mark_scratch, >> + }; >> + struct kho_radix_tree radix; >> + phys_addr_t prev_end = 0; >> + int err = 0; >> + >> + err = kho_radix_init_tree(&radix, NULL); >> + if (err) >> + goto print; >> + >> + /* Walk the KHO radix tree to find busy blocks. */ >> + err = kho_radix_walk_tree(&kho_in.radix_tree, &kho_cb, &radix); > > sashiko: Will this trigger a lockdep recursive locking warning? > > I think it will. It does indeed, but that's a false positive. These are different trees and so they have different mutexes. So I ignored this when sending the v5. But now that you also point it out, I went and did some digging. And I think I know how to fix this. Setting a different lockdep class for the local tree makes the warning go away. And from my sampling of other users of lockdep_set_class(), this does seem to be right right usage of the API, though I can't find much documentation on it. While trying to explain in a comment why this is needed, I also realized "radix" is not a descriptive name at all, and I renamed it to "busy_blocks". I'll send a v6 shortly with these changes. -- Regards, Pratyush Yadav