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[34.123.190.156]) by smtp.gmail.com with ESMTPSA id g15-20020a02b70f000000b0042bb13cb80fsm3520216jam.120.2023.09.04.11.08.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Sep 2023 11:08:09 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org, Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , "Paul E. McKenney" , Vlastimil Babka Cc: "Joel Fernandes (Google)" , Zhen Lei , rcu@vger.kernel.org, Zqiang , stable@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 1/2] mm/vmalloc: Add a safer version of find_vm_area() for debug Date: Mon, 4 Sep 2023 18:08:04 +0000 Message-ID: <20230904180806.1002832-1-joel@joelfernandes.org> X-Mailer: git-send-email 2.42.0.283.g2d96d420d3-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org It is unsafe to dump vmalloc area information when trying to do so from some contexts. Add a safer trylock version of the same function to do a best-effort VMA finding and use it from vmalloc_dump_obj(). [applied test robot feedback on unused function fix.] [applied Uladzislau feedback on locking.] Reported-by: Zhen Lei Cc: Paul E. McKenney Cc: rcu@vger.kernel.org Cc: Zqiang Reviewed-by: Uladzislau Rezki (Sony) Fixes: 98f180837a89 ("mm: Make mem_dump_obj() handle vmalloc() memory") Cc: stable@vger.kernel.org Signed-off-by: Joel Fernandes (Google) Reported-by: Zhen Lei Reviewed-by: Uladzislau Rezki (Sony) Signed-off-by: Joel Fernandes (Google) --- mm/vmalloc.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 93cf99aba335..2c6a0e2ff404 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -4274,14 +4274,32 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms) #ifdef CONFIG_PRINTK bool vmalloc_dump_obj(void *object) { - struct vm_struct *vm; void *objp = (void *)PAGE_ALIGN((unsigned long)object); + const void *caller; + struct vm_struct *vm; + struct vmap_area *va; + unsigned long addr; + unsigned int nr_pages; - vm = find_vm_area(objp); - if (!vm) + if (!spin_trylock(&vmap_area_lock)) + return false; + va = __find_vmap_area((unsigned long)objp, &vmap_area_root); + if (!va) { + spin_unlock(&vmap_area_lock); return false; + } + + vm = va->vm; + if (!vm) { + spin_unlock(&vmap_area_lock); + return false; + } + addr = (unsigned long)vm->addr; + caller = vm->caller; + nr_pages = vm->nr_pages; + spin_unlock(&vmap_area_lock); pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n", - vm->nr_pages, (unsigned long)vm->addr, vm->caller); + nr_pages, addr, caller); return true; } #endif