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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6C0F6C77B72 for ; Fri, 14 Apr 2023 20:54:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229713AbjDNUyk (ORCPT ); Fri, 14 Apr 2023 16:54:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49536 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229586AbjDNUyj (ORCPT ); Fri, 14 Apr 2023 16:54:39 -0400 Received: from wout1-smtp.messagingengine.com (wout1-smtp.messagingengine.com [64.147.123.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA70B3C33; Fri, 14 Apr 2023 13:54:37 -0700 (PDT) Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailout.west.internal (Postfix) with ESMTP id B653732009AF; Fri, 14 Apr 2023 16:54:34 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute2.internal (MEProxy); Fri, 14 Apr 2023 16:54:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=devkernel.io; h= cc:cc:content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=fm1; t=1681505674; x=1681592074; bh=rl FheFZweK49BGNnFZwEc5L1U+sCs9kJT/iFa/MIfcY=; b=u1KA8P2Tn9lh3rLH8/ IKeBdjNTCA2wxQNFIbuPaY07Py0Y0ltUhQ5goajpEAUVtiAwucxonhvnyocX3xux r56rJRVSFg+D6i+luKjatEQy+zj7s6s5kp0ebHYGPL1gdQE6sT9W5xe8loLNgDBi Okg7PEwo3ZS5VRbdFXExWzY/PKj8gAwMn05eBeZg2dTcPBfelIirqURrStGOGMIy n64Wugriv0ITNyunTinny1460VZb++52aAxFNEG+ziAECVtpIZ38pKGYnV+gCxm6 JaRaXfQcVuPDA/xmysVjeToN9qZVzsAmoTE07cuCUszwsn3W3+5yPaLUbX9LpuZo Jj6Q== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm3; t=1681505674; x=1681592074; bh=rlFheFZweK49B GNnFZwEc5L1U+sCs9kJT/iFa/MIfcY=; b=JWAQb6wJO0ZMS2m0H5Z1TIrf0S9I9 2pFUgxntkJmVV7z6EzbmF14L47kj4w4w8cdNK7SXSCHuNALtL47LC2OUQrPNFV2G jufOL8wePIOJQBUhgUxXz8ac8IIrG3YZwP6gzvdEuJ1hcRw4Fej95mcnVpQodorV 7o4kApOZCmJmIdX0+LoQYqwlhB5aM1pdCwBQ3v+0qTnnl2B9I1wOc1lCpshYX/0m 09esXPm4ImkltPrclx1Cvv2HQ5JTzhno98B4mi15ShIWlNCE/X1V7LW8CmB3+Eci H43Fv6HfGyeR3/sGO89BmaRzHDx5IowhLcWYgSxPgEgdzyDVOkXVZG7Rg== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrvdeltddgudehhecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enucfjughrpehffgfhvfevufffjgfkgggtsehttdertddtredtnecuhfhrohhmpefuthgv fhgrnhcutfhovghstghhuceoshhhrhesuggvvhhkvghrnhgvlhdrihhoqeenucggtffrrg htthgvrhhnpeevlefggffhheduiedtheejveehtdfhtedvhfeludetvdegieekgeeggfdu geeutdenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpe hshhhrseguvghvkhgvrhhnvghlrdhioh X-ME-Proxy: Feedback-ID: i84614614:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Fri, 14 Apr 2023 16:54:32 -0400 (EDT) References: <20230413233115.1878303-1-shr@devkernel.io> <20230413233115.1878303-2-shr@devkernel.io> User-agent: mu4e 1.10.1; emacs 28.2.50 From: Stefan Roesch To: David Hildenbrand Cc: kernel-team@fb.com, linux-mm@kvack.org, riel@surriel.com, mhocko@suse.com, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, akpm@linux-foundation.org, hannes@cmpxchg.org, willy@infradead.org, Bagas Sanjaya Subject: Re: [PATCH v7 1/3] mm: add new api to enable ksm per process Date: Fri, 14 Apr 2023 13:53:15 -0700 In-reply-to: Message-ID: MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org David Hildenbrand writes: > Thanks! > > In general, > > Acked-by: David Hildenbrand > > Two nits below, after staring at some other prctl implementations. > >> +#define PR_SET_MEMORY_MERGE 67 >> +#define PR_GET_MEMORY_MERGE 68 >> #endif /* _LINUX_PRCTL_H */ >> diff --git a/kernel/sys.c b/kernel/sys.c >> index 495cd87d9bf4..8c2e50edeb18 100644 >> --- a/kernel/sys.c >> +++ b/kernel/sys.c >> @@ -15,6 +15,7 @@ >> #include >> #include >> #include >> +#include >> #include >> #include >> #include >> @@ -2661,6 +2662,30 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, >> case PR_SET_VMA: >> error = prctl_set_vma(arg2, arg3, arg4, arg5); >> break; >> +#ifdef CONFIG_KSM >> + case PR_SET_MEMORY_MERGE: > > Looking at some other code (PR_SET_NO_NEW_PRIVS/ PR_SET_THP_DISABLE) I wonder if > we also want > > if (arg3 || arg4 || arg5) > return -EINVAL; > I added the above check. It requires that we always specify all parameters in the test programs. I also changed them accordingly. > For PR_GET_MEMORY_MERGE it looks good already. > >> + if (mmap_write_lock_killable(me->mm)) >> + return -EINTR; >> + >> + if (arg2) { >> + error = ksm_enable_merge_any(me->mm); >> + } else { >> + /* >> + * TODO: we might want disable KSM on all VMAs and >> + * trigger unsharing to completely disable KSM. >> + */ >> + clear_bit(MMF_VM_MERGE_ANY, &me->mm->flags); >> + error = 0; >> + } >> + mmap_write_unlock(me->mm); >> + break; >> + case PR_GET_MEMORY_MERGE: >> + if (arg2 || arg3 || arg4 || arg5) >> + return -EINVAL; >> + >> + error = !!test_bit(MMF_VM_MERGE_ANY, &me->mm->flags); >> + break; >> +#endif >> default: >> error = -EINVAL; >> break; > > [...] > >> +/** >> + * ksm_enable_merge_any - Add mm to mm ksm list and enable merging on all >> + * compatible VMA's >> + * >> + * @mm: Pointer to mm >> + * >> + * Returns 0 on success, otherwise error code >> + */ >> +int ksm_enable_merge_any(struct mm_struct *mm) >> +{ >> + int err; >> + >> + if (test_bit(MMF_VM_MERGE_ANY, &mm->flags)) >> + return -EINVAL; > > > I'm curious, why is enabling the prctl() supposed to fail if already enabled? > (it would not fail if disabling and already disabled) > I changed that to not return an error in that case. > > For example, PR_SET_THP_DISABLE/PR_SET_NO_NEW_PRIVS doesn't fail if already set.