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[59.167.251.205]) by smtp.gmail.com with ESMTPSA id b19sm3452810pgs.10.2019.08.29.17.40.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Aug 2019 17:40:05 -0700 (PDT) From: Daniel Axtens To: kasan-dev@googlegroups.com, linux-mm@kvack.org, x86@kernel.org, aryabinin@virtuozzo.com, glider@google.com, luto@kernel.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, dvyukov@google.com, christophe.leroy@c-s.fr Cc: linuxppc-dev@lists.ozlabs.org, gor@linux.ibm.com, Daniel Axtens Subject: [PATCH v5 5/5] kasan debug: track pages allocated for vmalloc shadow Date: Fri, 30 Aug 2019 10:38:21 +1000 Message-Id: <20190830003821.10737-6-dja@axtens.net> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190830003821.10737-1-dja@axtens.net> References: <20190830003821.10737-1-dja@axtens.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Provide the current number of vmalloc shadow pages in /sys/kernel/debug/kasan_vmalloc/shadow_pages. Signed-off-by: Daniel Axtens --- Merging this is probably overkill, but I leave it to the discretion of the broader community. On v4 (no dynamic freeing), I saw the following approximate figures on my test VM: - fresh boot: 720 - after test_vmalloc: ~14000 With v5 (lazy dynamic freeing): - boot: ~490-500 - running modprobe test_vmalloc pushes the figures up to sometimes as high as ~14000, but they drop down to ~560 after the test ends. I'm not sure where the extra sixty pages are from, but running the test repeately doesn't cause the number to keep growing, so I don't think we're leaking. - with vmap_stack, spawning tasks pushes the figure up to ~4200, then some clearing kicks in and drops it down to previous levels again. --- mm/kasan/common.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index c12a2e6ecff5..69f32f2857b0 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -35,6 +35,7 @@ #include #include #include +#include #include "kasan.h" #include "../slab.h" @@ -748,6 +749,8 @@ core_initcall(kasan_memhotplug_init); #endif #ifdef CONFIG_KASAN_VMALLOC +static u64 vmalloc_shadow_pages; + static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr, void *unused) { @@ -774,6 +777,7 @@ static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr, if (likely(pte_none(*ptep))) { set_pte_at(&init_mm, addr, ptep, pte); page = 0; + vmalloc_shadow_pages++; } spin_unlock(&init_mm.page_table_lock); if (page) @@ -833,6 +837,7 @@ static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr, pte_clear(&init_mm, addr, ptep); free_page(page); + vmalloc_shadow_pages--; spin_unlock(&init_mm.page_table_lock); return 0; @@ -887,4 +892,25 @@ void kasan_release_vmalloc(unsigned long start, unsigned long end, (unsigned long)(shadow_end - shadow_start), kasan_depopulate_vmalloc_pte, NULL); } + +static __init int kasan_init_vmalloc_debugfs(void) +{ + struct dentry *root, *count; + + root = debugfs_create_dir("kasan_vmalloc", NULL); + if (IS_ERR(root)) { + if (PTR_ERR(root) == -ENODEV) + return 0; + return PTR_ERR(root); + } + + count = debugfs_create_u64("shadow_pages", 0444, root, + &vmalloc_shadow_pages); + + if (IS_ERR(count)) + return PTR_ERR(root); + + return 0; +} +late_initcall(kasan_init_vmalloc_debugfs); #endif -- 2.20.1