linux-kernel - [PATCH -next 1/3] vmalloc: Choose a better start address in vm_area_register

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Date:   Mon, 5 Jul 2021 19:14:51 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <kasan-dev@...glegroups.com>,
        <linux-mm@...ck.org>, Kefeng Wang <wangkefeng.wang@...wei.com>
Subject: [PATCH -next 1/3] vmalloc: Choose a better start address in vm_area_register_early()

There are some fixed locations in the vmalloc area be reserved
in ARM(see iotable_init()) and ARM64(see map_kernel()), but for
pcpu_page_first_chunk(), it calls vm_area_register_early() and
choose VMALLOC_START as the start address of vmap area which
could be conflicted with above address, then could trigger a
BUG_ON in vm_area_add_early().

Let's choose the end of existing address range in vmlist as the
start address instead of VMALLOC_START to avoid the BUG_ON.

Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 mm/vmalloc.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d5cd52805149..a98cf97f032f 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2238,12 +2238,14 @@ void __init vm_area_add_early(struct vm_struct *vm)
  */
 void __init vm_area_register_early(struct vm_struct *vm, size_t align)
 {
-	static size_t vm_init_off __initdata;
+	unsigned long vm_start = VMALLOC_START;
+	struct vm_struct *tmp;
 	unsigned long addr;
 
-	addr = ALIGN(VMALLOC_START + vm_init_off, align);
-	vm_init_off = PFN_ALIGN(addr + vm->size) - VMALLOC_START;
+	for (tmp = vmlist; tmp; tmp = tmp->next)
+		vm_start = (unsigned long)tmp->addr + tmp->size;
 
+	addr = ALIGN(vm_start, align);
 	vm->addr = (void *)addr;
 
 	vm_area_add_early(vm);
-- 
2.26.2