linux-kernel - Re: Panic on kmemleak scan

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Date:   Tue, 12 Oct 2021 09:08:41 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
Cc:     lkml <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
        Catalin Marinas <catalin.marinas@....com>
Subject: Re: Panic on kmemleak scan

(added Catalin)

On Mon, Oct 11, 2021 at 02:23:31PM +0300, Vladimir Zapolskiy wrote:
> Hello Mike,
> 
> commit a7259df767 ("memblock: make memblock_find_in_range method private") [1]
> invokes a kernel panic while running kmemleak on OF platforms with nomaped
> regions, basically it's similar to an issue reported and fixed earlier by [2]:
> 
>   Unable to handle kernel paging request at virtual address ffff000021e00000

Does this virtual address correspond to a nomap area?

Can you check if this patch helps:

diff --git a/mm/memblock.c b/mm/memblock.c
index 184dcd2e5d99..5c3503c98b2f 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -936,7 +936,12 @@ int __init_memblock memblock_mark_mirror(phys_addr_t base, phys_addr_t size)
  */
 int __init_memblock memblock_mark_nomap(phys_addr_t base, phys_addr_t size)
 {
-	return memblock_setclr_flag(base, size, 1, MEMBLOCK_NOMAP);
+	int ret = memblock_setclr_flag(base, size, 1, MEMBLOCK_NOMAP);
+
+	if (!ret)
+		kmemleak_free_part_phys(base, size);
+
+	return ret;
 }
 
 /**

>   [...]
>     scan_block+0x64/0x170
>     scan_gray_list+0xe8/0x17c
>     kmemleak_scan+0x270/0x514
>     kmemleak_write+0x34c/0x4ac
> 
> I believe it would be a trivial problem to correct for you, thank you in
> advance!
> 
> [1] https://lore.kernel.org/all/20210816122622.30279-1-rppt@kernel.org/T/#u
> [2] https://lore.kernel.org/lkml/20190119132832.GA29881@MBP.local/t/#m032124f36c07
> 
> --
> Best wishes,
> Vladimir

-- 
Sincerely yours,
Mike.