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[34.86.47.53]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-559449647e0sm1776242e0c.3.2025.11.01.07.23.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 01 Nov 2025 07:23:38 -0700 (PDT) From: Pasha Tatashin To: akpm@linux-foundation.org, brauner@kernel.org, corbet@lwn.net, graf@amazon.com, jgg@ziepe.ca, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, masahiroy@kernel.org, ojeda@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, rdunlap@infradead.org, rppt@kernel.org, tj@kernel.org, yanjun.zhu@linux.dev Subject: [PATCH v9 4/9] memblock: Unpreserve memory in case of error Date: Sat, 1 Nov 2025 10:23:20 -0400 Message-ID: <20251101142325.1326536-5-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.51.1.930.gacf6e81ea2-goog In-Reply-To: <20251101142325.1326536-1-pasha.tatashin@soleen.com> References: <20251101142325.1326536-1-pasha.tatashin@soleen.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" If there is an error half way through KHO memory preservation, we should rollback and unpreserve everything that is partially preserved. Signed-off-by: Pasha Tatashin Suggested-by: Pratyush Yadav Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Pratyush Yadav --- mm/memblock.c | 73 ++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 58 insertions(+), 15 deletions(-) diff --git a/mm/memblock.c b/mm/memblock.c index e3bef9b35d63..f527ad1ca682 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -2445,29 +2445,60 @@ int reserve_mem_release_by_name(const char *name) #define MEMBLOCK_KHO_NODE_COMPATIBLE "memblock-v1" #define RESERVE_MEM_KHO_NODE_COMPATIBLE "reserve-mem-v1" =20 +static int __init reserved_mem_preserve(void) +{ + unsigned int nr_preserved =3D 0; + int err; + + for (unsigned int i =3D 0; i < reserved_mem_count; i++, nr_preserved++) { + struct reserve_mem_table *map =3D &reserved_mem_table[i]; + struct page *page =3D phys_to_page(map->start); + unsigned int nr_pages =3D map->size >> PAGE_SHIFT; + + err =3D kho_preserve_pages(page, nr_pages); + if (err) + goto err_unpreserve; + } + + return 0; + +err_unpreserve: + for (unsigned int i =3D 0; i < nr_preserved; i++) { + struct reserve_mem_table *map =3D &reserved_mem_table[i]; + struct page *page =3D phys_to_page(map->start); + unsigned int nr_pages =3D map->size >> PAGE_SHIFT; + + kho_unpreserve_pages(page, nr_pages); + } + + return err; +} + static int __init prepare_kho_fdt(void) { - int err =3D 0, i; struct page *fdt_page; void *fdt; + int err; =20 fdt_page =3D alloc_page(GFP_KERNEL); - if (!fdt_page) - return -ENOMEM; + if (!fdt_page) { + err =3D -ENOMEM; + goto err_no_fdt_page; + } =20 fdt =3D page_to_virt(fdt_page); + err =3D kho_preserve_pages(fdt_page, 1); + if (err) + goto err_free_fdt; =20 err |=3D fdt_create(fdt, PAGE_SIZE); err |=3D fdt_finish_reservemap(fdt); - err |=3D fdt_begin_node(fdt, ""); err |=3D fdt_property_string(fdt, "compatible", MEMBLOCK_KHO_NODE_COMPATI= BLE); - for (i =3D 0; i < reserved_mem_count; i++) { + + for (unsigned int i =3D 0; !err && i < reserved_mem_count; i++) { struct reserve_mem_table *map =3D &reserved_mem_table[i]; - struct page *page =3D phys_to_page(map->start); - unsigned int nr_pages =3D map->size >> PAGE_SHIFT; =20 - err |=3D kho_preserve_pages(page, nr_pages); err |=3D fdt_begin_node(fdt, map->name); err |=3D fdt_property_string(fdt, "compatible", RESERVE_MEM_KHO_NODE_COM= PATIBLE); err |=3D fdt_property(fdt, "start", &map->start, sizeof(map->start)); @@ -2477,15 +2508,27 @@ static int __init prepare_kho_fdt(void) err |=3D fdt_end_node(fdt); err |=3D fdt_finish(fdt); =20 - err |=3D kho_preserve_folio(page_folio(fdt_page)); + if (err) + goto err_unpreserve_fdt; =20 - if (!err) - err =3D kho_add_subtree(MEMBLOCK_KHO_FDT, fdt); + err =3D kho_add_subtree(MEMBLOCK_KHO_FDT, fdt); + if (err) + goto err_unpreserve_fdt; =20 - if (err) { - pr_err("failed to prepare memblock FDT for KHO: %d\n", err); - put_page(fdt_page); - } + err =3D reserved_mem_preserve(); + if (err) + goto err_remove_subtree; + + return 0; + +err_remove_subtree: + kho_remove_subtree(fdt); +err_unpreserve_fdt: + kho_unpreserve_pages(fdt_page, 1); +err_free_fdt: + put_page(fdt_page); +err_no_fdt_page: + pr_err("failed to prepare memblock FDT for KHO: %d\n", err); =20 return err; } --=20 2.51.1.930.gacf6e81ea2-goog