linux-kernel - [PATCH 2/6] kexec: delete a useless check in crash_shrink

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Message-ID: <20230527123439.772-3-thunder.leizhen@huawei.com>
Date:   Sat, 27 May 2023 20:34:35 +0800
From:   Zhen Lei <thunder.leizhen@...wei.com>
To:     Eric Biederman <ebiederm@...ssion.com>,
        Baoquan He <bhe@...hat.com>, <kexec@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
CC:     Zhen Lei <thunder.leizhen@...wei.com>,
        Michael Holzheu <holzheu@...ux.vnet.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Amerigo Wang <amwang@...hat.com>
Subject: [PATCH 2/6] kexec: delete a useless check in crash_shrink_memory()

The check '(crashk_res.parent != NULL)' is added by
commit e05bd3367bd3 ("kexec: fix Oops in crash_shrink_memory()"), but it's
stale now. Because if 'crashk_res' is not reserved, it will be zero in
size and will be intercepted by the above 'if (new_size >= old_size)'.

Ago:
	if (new_size >= end - start + 1)

Now:
	old_size = (end == 0) ? 0 : end - start + 1;
	if (new_size >= old_size)

Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
---
 kernel/kexec_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 22acee18195a591..d1ab139dd49035e 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1137,7 +1137,7 @@ int crash_shrink_memory(unsigned long new_size)
 	end = start + new_size;
 	crash_free_reserved_phys_range(end, crashk_res.end);
 
-	if ((start == end) && (crashk_res.parent != NULL))
+	if (start == end)
 		release_resource(&crashk_res);
 
 	ram_res->start = end;
-- 
2.25.1