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Message-ID: <1720516658-50434-1-git-send-email-zhang.chuna@h3c.com>
Date: Tue, 9 Jul 2024 17:17:38 +0800
From: zhangchun <zhang.chuna@....com>
To: <akpm@...ux-foundation.org>
CC: <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>, <jiaoxupo@....com>,
<zhang.zhengming@....com>, <zhang.zhansheng@....com>,
<shaohaojize@....com>, zhangchun <zhang.chuna@....com>
Subject: [PATCH] mm: Give kmap_lock before call flush_tlb_kernel_rang,avoid kmap_high deadlock.
Use kmap_high and kmap_XXX or kumap_xxx among differt cores at the same
time may cause deadlock. The issue is like this:
CPU 0: CPU 1:
kmap_high(){ kmap_xxx() {
... irq_disable();
spin_lock(&kmap_lock)
...
map_new_virtual ...
flush_all_zero_pkmaps
flush_tlb_kernel_range /* CPU0 holds the kmap_lock */
smp_call_function_many spin_lock(&kmap_lock)
... ....
spin_unlock(&kmap_lock)
...
CPU 0 holds the kmap_lock, waiting for CPU 1 respond to IPI. But CPU 1
has disabled irqs, waiting for kmap_lock, cannot answer the IPI. Fix
this by releasing kmap_lock before call flush_tlb_kernel_range,
avoid kmap_lock deadlock.
Fixes: 3297e760776a ("highmem: atomic highmem kmap page pinning")
Signed-off-by: zhangchun <zhang.chuna@....com>
Co-developed-by: zhangzhansheng <zhang.zhansheng@....com>
Signed-off-by: zhangzhansheng <zhang.zhansheng@....com>
Reviewed-by: zhangzhengming <zhang.zhengming@....com>
---
mm/highmem.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/highmem.c b/mm/highmem.c
index bd48ba4..841b370 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -220,8 +220,11 @@ static void flush_all_zero_pkmaps(void)
set_page_address(page, NULL);
need_flush = 1;
}
- if (need_flush)
+ if (need_flush) {
+ spin_unlock(&kmap_lock);
flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
+ spin_lock(&kmap_lock);
+ }
}
void __kmap_flush_unused(void)
--
1.8.3.1
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