From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72EDCE95A8E for ; Mon, 9 Oct 2023 14:58:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D77688D007D; Mon, 9 Oct 2023 10:58:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D27CD8D0031; Mon, 9 Oct 2023 10:58:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C161A8D007D; Mon, 9 Oct 2023 10:58:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id B164A8D0031 for ; Mon, 9 Oct 2023 10:58:22 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 4F6C2C0314 for ; 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charset=us-ascii Content-Disposition: inline In-Reply-To: <20231008023317.3015699-4-liushixin2@huawei.com> X-Rspam-User: X-Stat-Signature: ru4744jf1fccdepi66tn7m5trupokzb8 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 4419C100012 X-HE-Tag: 1696863498-222109 X-HE-Meta: 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 +vhMEKfD 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, Oct 08, 2023 at 10:33:16AM +0800, Liu Shixin wrote: > delete_object_part() can be called by multiple callers in the same time. > If an object is found and removed by a caller, and then another caller > try to find it too, it failed and return directly. The secound part still > be recorded by kmemleak even if it has alreadly been freed to buddy. > With DEBUG on, kmemleak will report the following warning: > > kmemleak: Partially freeing unknown object at 0xa1af86000 (size 4096) > CPU: 0 PID: 742 Comm: test_huge Not tainted 6.6.0-rc3kmemleak+ #54 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 > Call Trace: > > dump_stack_lvl+0x37/0x50 > kmemleak_free_part_phys+0x50/0x60 > hugetlb_vmemmap_optimize+0x172/0x290 > ? __pfx_vmemmap_remap_pte+0x10/0x10 > __prep_new_hugetlb_folio+0xe/0x30 > prep_new_hugetlb_folio.isra.0+0xe/0x40 > alloc_fresh_hugetlb_folio+0xc3/0xd0 > alloc_surplus_hugetlb_folio.constprop.0+0x6e/0xd0 > hugetlb_acct_memory.part.0+0xe6/0x2a0 > hugetlb_reserve_pages+0x110/0x2c0 > hugetlbfs_file_mmap+0x11d/0x1b0 > mmap_region+0x248/0x9a0 > ? hugetlb_get_unmapped_area+0x15c/0x2d0 > do_mmap+0x38b/0x580 > vm_mmap_pgoff+0xe6/0x190 > ksys_mmap_pgoff+0x18a/0x1f0 > do_syscall_64+0x3f/0x90 > entry_SYSCALL_64_after_hwframe+0x6e/0xd8 > > Fix the problem by adding a new mutex lock to make sure all objects are > deleted sequentially in delete_object_part(). The kmemleak_lock is not > suitable here because there is a memory allocation with flag GFP_KERNEL. > > Fixes: 53238a60dd4a ("kmemleak: Allow partial freeing of memory blocks") > Signed-off-by: Liu Shixin > --- > mm/kmemleak.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/mm/kmemleak.c b/mm/kmemleak.c > index 54c2c90d3abc..ed497866361a 100644 > --- a/mm/kmemleak.c > +++ b/mm/kmemleak.c > @@ -208,6 +208,8 @@ static struct rb_root object_tree_root = RB_ROOT; > static struct rb_root object_phys_tree_root = RB_ROOT; > /* protecting the access to object_list, object_tree_root (or object_phys_tree_root) */ > static DEFINE_RAW_SPINLOCK(kmemleak_lock); > +/* Serial delete_object_part() to ensure all objects are deleted correctly */ > +static DEFINE_MUTEX(delete_object_part_mutex); I mentioned in my reply on v1, do we actually need a lock at all? https://lore.kernel.org/r/ZRRhDgR/SIxbOCDk@arm.com I think we can rework the core a bit to only use kmemleak_lock. We could use GFP_ATOMIC when invoking __create_object(), it won't matter much as partial freeing is used rarely and only during boot. Alternatively, we could allocate two objects outside the lock and just pass them to a new, modified __create_object() function which would avoid re-allocation. The mutex looks simpler but then we need to be careful we only calls these functions in a sleepable context. -- Catalin