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b=o7FW2XxXRBGQ8nfAo9dFMeDzenLwFr5eECqJwnbVmgMyiw5p8jdDRLdXgOrXzTjJj 7x6AbZ9eMVptgkc4wbEdnNy/O+Iv3N7nTo8ftFOhKFmXVdl95Wbn3dETbq4sPA5LIx kPTVdQK0EgSHXiqD1o2sgdnc7GhQna80NaZglPCQ+hvuHHKx9E101fHPbvR3a2KzmB Ju6MC6ubbO+lT+62igLLYQ8cEYJXv+G1AOlo4Y4Y5Jn1PgtUBfotQPCc00nKWfaYty 0KV46X6QjdM1qQaKlR7TE13d3puNKJkj/veUh76++YNF/iHFIRlNStUuARkvttHjwR imhnJT0gJCRdA== From: Pratyush Yadav To: Mike Rapoport Cc: Pratyush Yadav , Pasha Tatashin , Alexander Graf , Muchun Song , Oscar Salvador , David Hildenbrand , Andrew Morton , Jason Miu , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 02/12] kho: store incoming radix tree in kho_in In-Reply-To: (Mike Rapoport's message of "Mon, 11 May 2026 14:43:22 +0300") References: <20260429133928.850721-1-pratyush@kernel.org> <20260429133928.850721-3-pratyush@kernel.org> Date: Mon, 11 May 2026 18:28:21 +0200 Message-ID: <2vxz4ikddi6y.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C9C9C4000D X-Rspam-User: X-Stat-Signature: oc19unu7n9kaun9e4cumt7h53t3rp5f6 X-HE-Tag: 1778516905-448598 X-HE-Meta: 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 bwAnV2lR f0ovfbcgjuhPykjAWWqGltCa2Izhga08S7GurmcI03Dq2d1HpNJ9ysDUX+pFHahCaECDM+LAGjOsiqg7nuz9g6BKWKk4jpgxDKOr5KCuc4LCjSrW81YiSN6MlQZrz4oDMrz+4jlYZHeGpOc9x7X7fZUn/glgF+V+pC/BYIuH+lBvfiXL4zgcOWnF+khBMJSAm9El7LgTDZwDK++D14aUl971UscLD4uv0t7zRWS++VFQHDRbyhM3Seq87tA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, May 11 2026, Mike Rapoport wrote: > On Wed, Apr 29, 2026 at 03:39:04PM +0200, Pratyush Yadav wrote: >> From: "Pratyush Yadav (Google)" >> >> This allows other functions to also use the radix tree. While at it, >> also use kho_get_mem_map_phys() instead of duplicating the code to get >> the radix tree root from the FDT. >> >> Signed-off-by: Pratyush Yadav (Google) >> --- >> kernel/liveupdate/kexec_handover.c | 27 ++++++++------------------- >> 1 file changed, 8 insertions(+), 19 deletions(-) >> >> diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c >> index ba568d34c5b4..5758dc6fab5d 100644 >> --- a/kernel/liveupdate/kexec_handover.c >> +++ b/kernel/liveupdate/kexec_handover.c >> @@ -1294,6 +1294,7 @@ struct kho_in { >> char previous_release[__NEW_UTS_LEN + 1]; >> u32 kexec_count; >> struct kho_debugfs dbg; >> + struct kho_radix_tree radix_tree; >> }; >> >> static struct kho_in kho_in = { >> @@ -1373,24 +1374,10 @@ EXPORT_SYMBOL_GPL(kho_retrieve_subtree); >> >> static int __init kho_mem_retrieve(const void *fdt) >> { >> - struct kho_radix_tree tree; >> - const phys_addr_t *mem; >> - int len; >> - >> - /* Retrieve the KHO radix tree from passed-in FDT. */ >> - mem = fdt_getprop(fdt, 0, KHO_FDT_MEMORY_MAP_PROP_NAME, &len); >> - >> - if (!mem || len != sizeof(*mem)) { >> - pr_err("failed to get preserved KHO memory tree\n"); >> - return -ENOENT; >> - } >> - >> - if (!*mem) >> - return -EINVAL; >> - >> - tree.root = phys_to_virt(*mem); >> - mutex_init(&tree.lock); >> - return kho_radix_walk_tree(&tree, kho_preserved_memory_reserve); >> + kho_in.radix_tree.root = phys_to_virt(kho_get_mem_map_phys(fdt)); > > Do we really want to remove an explicit check for 0 and get a WARN() in > kho_radix_walk_tree()? If mem_map_phys is 0 then kho_populate() never sets kho_in.scratch_phys and thus kho_mem_retrieve() never gets called. So here it will never be 0, and if it is, a WARN() is certainly warranted. Perhaps I should add a comment since this isn't so obvious? > >> + mutex_init(&kho_in.radix_tree.lock); >> + return kho_radix_walk_tree(&kho_in.radix_tree, >> + kho_preserved_memory_reserve); >> } >> >> static __init int kho_out_fdt_setup(void) >> @@ -1597,8 +1584,10 @@ void __init kho_memory_init(void) >> if (kho_in.scratch_phys) { >> kho_scratch = phys_to_virt(kho_in.scratch_phys); >> >> - if (kho_mem_retrieve(kho_get_fdt())) >> + if (kho_mem_retrieve(kho_get_fdt())) { >> kho_in.fdt_phys = 0; >> + kho_in.radix_tree.root = NULL; > > I'd make kho_mem_retrieve() void and put these there. Sure, will do. > >> + } >> } else { >> kho_reserve_scratch(); >> } >> -- >> 2.54.0.545.g6539524ca2-goog >> -- Regards, Pratyush Yadav