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([114.29.24.243]) by smtp.gmail.com with ESMTPSA id a7-20020aa795a7000000b0050dc76281e6sm566385pfk.192.2022.05.05.00.01.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 May 2022 00:01:14 -0700 (PDT) From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Alexander Potapenko , Marco Elver , Dmitry Vyukov , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hyeonggon Yoo <42.hyeyoo@gmail.com> Subject: [PATCH] mm/kfence: reset PG_slab and memcg_data before freeing __kfence_pool Date: Thu, 5 May 2022 16:01:05 +0900 Message-Id: <20220505070105.1835745-1-42.hyeyoo@gmail.com> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" When kfence fails to initialize kfence pool, it frees the pool. But it does not reset PG_slab flag and memcg_data of struct page. Below is a BUG because of this. Let's fix it by resetting PG_slab and memcg_data before free. [ 0.089149] BUG: Bad page state in process swapper/0 pfn:3d8e06 [ 0.089149] page:ffffea46cf638180 refcount:0 mapcount:0 mapping:00000000= 00000000 index:0x0 pfn:0x3d8e06 [ 0.089150] memcg:ffffffff94a475d1 [ 0.089150] flags: 0x17ffffc0000200(slab|node=3D0|zone=3D2|lastcpupid=3D= 0x1fffff) [ 0.089151] raw: 0017ffffc0000200 ffffea46cf638188 ffffea46cf638188 0000= 000000000000 [ 0.089152] raw: 0000000000000000 0000000000000000 00000000ffffffff ffff= ffff94a475d1 [ 0.089152] page dumped because: page still charged to cgroup [ 0.089153] Modules linked in: [ 0.089153] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G B W 5.= 18.0-rc1+ #965 [ 0.089154] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS = 1.14.0-2 04/01/2014 [ 0.089154] Call Trace: [ 0.089155] [ 0.089155] dump_stack_lvl+0x49/0x5f [ 0.089157] dump_stack+0x10/0x12 [ 0.089158] bad_page.cold+0x63/0x94 [ 0.089159] check_free_page_bad+0x66/0x70 [ 0.089160] __free_pages_ok+0x423/0x530 [ 0.089161] __free_pages_core+0x8e/0xa0 [ 0.089162] memblock_free_pages+0x10/0x12 [ 0.089164] memblock_free_late+0x8f/0xb9 [ 0.089165] kfence_init+0x68/0x92 [ 0.089166] start_kernel+0x789/0x992 [ 0.089167] x86_64_start_reservations+0x24/0x26 [ 0.089168] x86_64_start_kernel+0xa9/0xaf [ 0.089170] secondary_startup_64_no_verify+0xd5/0xdb [ 0.089171] Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Reported-by: kernel test robot --- mm/kfence/core.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/kfence/core.c b/mm/kfence/core.c index a203747ad2c0..2ab3d473321e 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -642,6 +642,13 @@ static bool __init kfence_init_pool_early(void) * fails for the first page, and therefore expect addr=3D=3D__kfence_pool= in * most failure cases. */ + for (char *p =3D (char *)addr; p < __kfence_pool + KFENCE_POOL_SIZE; p += =3D PAGE_SIZE) { + struct page *page; + + page =3D virt_to_page(p); + page->memcg_data =3D 0; + __ClearPageSlab(page); + } memblock_free_late(__pa(addr), KFENCE_POOL_SIZE - (addr - (unsigned long)= __kfence_pool)); __kfence_pool =3D NULL; return false; --=20 2.32.0