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McKenney" , Zhang Qiang1 Subject: [PATCH] mm/vmalloc: allow mem_dump_obj() to be called in interrupt context Date: Sat, 12 Nov 2022 20:15:37 +0800 Message-ID: <20221112121537.1634-1-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.37.3.windows.1 MIME-Version: 1.0 X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1749293672354272846?= X-GMAIL-MSGID: =?utf-8?q?1749293672354272846?= The function mem_dump_obj() can sometimes provide valuable debugging information, but it cannot be called in an interrupt context because spinlock vmap_area_lock has not been protected against IRQs. If the current task has held the lock before hard/soft interrupt handler calls mem_dump_obj(), simply abandoning the dump operation can avoid deadlock. That is, no deadlock occurs in extreme cases, and dump succeeds in most cases. Signed-off-by: Zhen Lei --- mm/vmalloc.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index ccaa461998f3c37..cdd36c5a1aa16f8 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -4034,6 +4034,9 @@ bool vmalloc_dump_obj(void *object) struct vm_struct *vm; void *objp = (void *)PAGE_ALIGN((unsigned long)object); + if (unlikely(spin_is_locked(&vmap_area_lock))) + return false; + vm = find_vm_area(objp); if (!vm) return false;