From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C107E80C14 for ; Fri, 26 Apr 2024 04:07:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714104462; cv=none; b=Yw9k7Fj7wFo1wYCs+oSVPBqGaGB/TPVYH5nqXlkmYbbQnO/opTHNB3kqvTC1/I5nPd6LQPHH7ZPNxdDTdULscNZdXrIoOipubvN3Q8wiZjurfBqiYQrQnkFGrgvhxiHN/gPCOfHk0PH8v8I9Om+w83iWjQtLhJzih/wnXeYmg9w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714104462; c=relaxed/simple; bh=Ohnnnx0L3tg91UF4tIY8FT3teO8pZm0hf+x2QJVrheM=; h=Date:To:From:Subject:Message-Id; b=PkZFEm2tkaH2VeOmoB8CLdqOUynl5eElsYdNHsmmr2zjYJ2WJT9iQcFUqSIQfjYzGvVtOj40Lioir6OLAhC57TQRP0+S5lmqpmD2ejh/cMcLTyMI1Sl5rjlFgJ+whpNm84TX1KFP7yybSvI2E/Ws0GjSAdpvqIWG0BwULCnQ+EE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=wfQ9o/hD; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="wfQ9o/hD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 941C7C113CD; Fri, 26 Apr 2024 04:07:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1714104462; bh=Ohnnnx0L3tg91UF4tIY8FT3teO8pZm0hf+x2QJVrheM=; h=Date:To:From:Subject:From; b=wfQ9o/hDl4Zi4fpKVyoNSlWWfGhZ6mT1l+UgX1wZAdaLiSBCfDM2zUdVUc/Y/vPat /7gNMtIsxP9wBJ+cdd1y6MTvKzfPr194krOPWM5jiK/U7v6Vuw07iZXi4ASse6u8dL dRhvxfCIZ3oXedgHr5RQSorxibrNr+rxbY1PpvOg= Date: Thu, 25 Apr 2024 21:07:42 -0700 To: mm-commits@vger.kernel.org,willy@infradead.org,will@kernel.org,viro@ZenIV.linux.org.uk,oleg@redhat.com,keescook@chromium.org,jack@suse.cz,ebiederm@xmission.com,Dave.Martin@arm.com,catalin.marinas@arm.com,broonie@kernel.org,brauner@kernel.org,dianders@chromium.org,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-nonmm-stable] regset-use-kvzalloc-for-regset_get_alloc.patch removed from -mm tree Message-Id: <20240426040742.941C7C113CD@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: regset: use kvzalloc() for regset_get_alloc() has been removed from the -mm tree. Its filename was regset-use-kvzalloc-for-regset_get_alloc.patch This patch was dropped because it was merged into the mm-nonmm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Douglas Anderson Subject: regset: use kvzalloc() for regset_get_alloc() Date: Mon, 5 Feb 2024 09:26:30 -0800 While browsing through ChromeOS crash reports, I found one with an allocation failure that looked like this: chrome: page allocation failure: order:7, mode:0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), nodemask=(null),cpuset=urgent,mems_allowed=0 CPU: 7 PID: 3295 Comm: chrome Not tainted 5.15.133-20574-g8044615ac35c #1 (HASH:1162 1) Hardware name: Google Lazor (rev3 - 8) with KB Backlight (DT) Call trace: ... warn_alloc+0x104/0x174 __alloc_pages+0x5f0/0x6e4 kmalloc_order+0x44/0x98 kmalloc_order_trace+0x34/0x124 __kmalloc+0x228/0x36c __regset_get+0x68/0xcc regset_get_alloc+0x1c/0x28 elf_core_dump+0x3d8/0xd8c do_coredump+0xeb8/0x1378 get_signal+0x14c/0x804 ... An order 7 allocation is (1 << 7) contiguous pages, or 512K. It's not a surprise that this allocation failed on a system that's been running for a while. More digging showed that it was fairly easy to see the order 7 allocation by just sending a SIGQUIT to chrome (or other processes) to generate a core dump. The actual amount being allocated was 279,584 bytes and it was for "core_note_type" NT_ARM_SVE. There was quite a bit of discussion [1] on the mailing lists in response to my v1 patch attempting to switch to vmalloc. The overall conclusion was that we could likely reduce the 279,584 byte allocation by quite a bit and Mark Brown has sent a patch to that effect [2]. However even with the 279,584 byte allocation gone there are still 65,552 byte allocations. These are just barely more than the 65,536 bytes and thus would require an order 5 allocation. An order 5 allocation is still something to avoid unless necessary and nothing needs the memory here to be contiguous. Change the allocation to kvzalloc() which should still be efficient for small allocations but doesn't force the memory subsystem to work hard (and maybe fail) at getting a large contiguous chunk. [1] https://lore.kernel.org/r/20240201171159.1.Id9ad163b60d21c9e56c2d686b0cc9083a8ba7924@changeid [2] https://lore.kernel.org/r/20240203-arm64-sve-ptrace-regset-size-v1-1-2c3ba1386b9e@kernel.org Link: https://lkml.kernel.org/r/20240205092626.v2.1.Id9ad163b60d21c9e56c2d686b0cc9083a8ba7924@changeid Signed-off-by: Douglas Anderson Reviewed-by: Catalin Marinas Cc: Al Viro Cc: Christian Brauner Cc: Dave Martin Cc: Eric Biederman Cc: Jan Kara Cc: Kees Cook Cc: Mark Brown Cc: Matthew Wilcox (Oracle) Cc: Oleg Nesterov Cc: Will Deacon Signed-off-by: Andrew Morton --- fs/binfmt_elf.c | 2 +- kernel/regset.c | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) --- a/fs/binfmt_elf.c~regset-use-kvzalloc-for-regset_get_alloc +++ a/fs/binfmt_elf.c @@ -1928,7 +1928,7 @@ static void free_note_info(struct elf_no threads = t->next; WARN_ON(t->notes[0].data && t->notes[0].data != &t->prstatus); for (i = 1; i < info->thread_notes; ++i) - kfree(t->notes[i].data); + kvfree(t->notes[i].data); kfree(t); } kfree(info->psinfo.data); --- a/kernel/regset.c~regset-use-kvzalloc-for-regset_get_alloc +++ a/kernel/regset.c @@ -16,14 +16,14 @@ static int __regset_get(struct task_stru if (size > regset->n * regset->size) size = regset->n * regset->size; if (!p) { - to_free = p = kzalloc(size, GFP_KERNEL); + to_free = p = kvzalloc(size, GFP_KERNEL); if (!p) return -ENOMEM; } res = regset->regset_get(target, regset, (struct membuf){.p = p, .left = size}); if (res < 0) { - kfree(to_free); + kvfree(to_free); return res; } *data = p; @@ -71,6 +71,6 @@ int copy_regset_to_user(struct task_stru ret = regset_get_alloc(target, regset, size, &buf); if (ret > 0) ret = copy_to_user(data, buf, ret) ? -EFAULT : 0; - kfree(buf); + kvfree(buf); return ret; } _ Patches currently in -mm which might be from dianders@chromium.org are