Received: by 2002:a05:6a10:eb17:0:0:0:0 with SMTP id hx23csp61814pxb; Thu, 2 Sep 2021 19:20:44 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy+WCN7eZbaxJGBWqVK4Ub+yAHVcMPfnWrw+1BDctVQ+5tJHKjyTTo7KdErMC9RM+zoCkOd X-Received: by 2002:a02:850a:: with SMTP id g10mr692428jai.134.1630635643928; Thu, 02 Sep 2021 19:20:43 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1630635643; cv=none; d=google.com; s=arc-20160816; b=Q8Y3XFHRXSG6/H12mqIzUFOcBXQSk+gsZChKBNjXC09orK/8j0FzgL9268rQIpA8aN IhHK/aqsWK276ZqYBlPSKIgI0WM3Jd9elyXCBgAmMhjcBdFOIJKFlXrDQhdy8oPZYLxW lKwy+b1uZrLxli0VkeYr4osuBIFeHfw8lgp9CtJKN1VKEhfLyjNp8zKCMRTk/VA2MoIc ysR0Pjyiby7Ck+z7VAdLhL2Bav6+5QucNEkqxuZdc5YlIVwDR6GJRuv1AaHc2S4xRCy7 IG9KVe30AwR9E8HuAeXFAJVLJc9xUKgQ1ctlACaL1VB/mU9dBCXU0CmLbLXDJaNk4SAG cYiw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:subject:message-id:date:from:in-reply-to :references:mime-version:dkim-signature; bh=U9SaGHSuOXCrItgAbBPYGhsYiz2vs3ute8NQFPvnaUQ=; b=Qt2kgK4EalrxlbosQAAQyjnAfYRabFsW14ibpklyt2SYV9U0YwMT2dvhUh1w7rSqE2 PErsBQB1pPhi3aQYzhC1swM2F8yJzLKDRiSXmx5465MWogIzshj3XqE19h200OvTstRg SRdC6Kt9K9Be0bcrR47D3cHsXCGZWxGo+nR0Qy6JBAH7nlYlY6gnwMyv5pUTe1/wVGqG Nk+yH71WV13impFV926Nd5f9QkFvLJWduR4YTHD+yC+a1xJctQSGDapJnmavqB6Cxriz ZE1I+JczzuMYpH2RJY3TRtDwK7jOX3rHxyvxp0JHnQQKHHimKFjlbm+nj4faDerJP8r/ 1CaQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=V6AgF1x9; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id l10si4639252ios.26.2021.09.02.19.20.31; Thu, 02 Sep 2021 19:20:43 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=V6AgF1x9; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234366AbhICAaN (ORCPT + 99 others); Thu, 2 Sep 2021 20:30:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46662 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239645AbhICAaK (ORCPT ); Thu, 2 Sep 2021 20:30:10 -0400 Received: from mail-yb1-xb36.google.com (mail-yb1-xb36.google.com [IPv6:2607:f8b0:4864:20::b36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B2CABC061760 for ; Thu, 2 Sep 2021 17:29:11 -0700 (PDT) Received: by mail-yb1-xb36.google.com with SMTP id z5so7146903ybj.2 for ; Thu, 02 Sep 2021 17:29:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=U9SaGHSuOXCrItgAbBPYGhsYiz2vs3ute8NQFPvnaUQ=; b=V6AgF1x9oVWCjF2hTKLjoxWgqPgnmoYwiACxC56iF1TZ9hdA+2iGh3TRshNQb2Qvha QF66aXDqKrmni2DXQRZNAaGniJ2MBXiTn2qJ4XXB0qhtWUNqxNOEUz6phOkV6YtzMNzz 1VXyU64s2wAFu4FkYPt05FDGiVbGZnZ9NCjDCl3Z2Qh+6NtIckL+GqNUQI85hV9XdRYa nM8GYTq8y306Cq3RX514UlqQmx37SSI9GxtkG6lRS8D/RXXICnVeeH1lMT1xsbYtqPLC ayf+V28SOtV2YV06ICcOKSmZ/tbsQLOMdvOMLB1y/P0r+RpjZz5yJo5PWyZ4Fd7RgrDE 1bGg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=U9SaGHSuOXCrItgAbBPYGhsYiz2vs3ute8NQFPvnaUQ=; b=dpGjF/SmYWXoY+0Lgflv3Y5eW8Z6xQtHXfCWcJk0Js5KrQLYZU4gsBFqCPqIRTEQAa vF5PAqtq3i3h0AxXBbTv+KuaohN4VlALhAHc8LEb9JwK6hAaHhsctrAsY0Y3SvzicT0B QfDHxNB5C9r/i2f38rP5P2heZPEsK2iQ1ClZYKUhHUTCGpj4gPoaI9e8n1TW8yH1bfv6 O7T29JVS4R01zG7/IePBaJPZZsloqkMiYN9Uqfp3bpt6JBjhMXm2mz2nFVbqsN/UyoGe /lm80LlD6tvgXvdOPfOEMPhjd3nPvA96QRWwnICeqT+xrsoV1RbDHIaJLojiKreE1tLM MSyA== X-Gm-Message-State: AOAM5333B30hy+b116LNRB357mrfP2FVXEm8NedLa0+i8H56OwxmTDqL t8S6sjv19QF5ZrrYM1hPI5TNYFFmfd58V7pX49pjMQ== X-Received: by 2002:a25:49c2:: with SMTP id w185mr1274569yba.294.1630628950482; Thu, 02 Sep 2021 17:29:10 -0700 (PDT) MIME-Version: 1.0 References: <20210902231813.3597709-1-surenb@google.com> In-Reply-To: <20210902231813.3597709-1-surenb@google.com> From: Suren Baghdasaryan Date: Thu, 2 Sep 2021 17:28:59 -0700 Message-ID: Subject: Re: [PATCH v9 1/3] mm: rearrange madvise code to allow for reuse To: Andrew Morton Cc: Colin Cross , Sumit Semwal , Michal Hocko , Dave Hansen , Kees Cook , Matthew Wilcox , "Kirill A . Shutemov" , Vlastimil Babka , Johannes Weiner , Jonathan Corbet , Al Viro , Randy Dunlap , Kalesh Singh , Peter Xu , rppt@kernel.org, Peter Zijlstra , Catalin Marinas , vincenzo.frascino@arm.com, =?UTF-8?B?Q2hpbndlbiBDaGFuZyAo5by16Yym5paHKQ==?= , Axel Rasmussen , Andrea Arcangeli , Jann Horn , apopple@nvidia.com, John Hubbard , Yu Zhao , Will Deacon , fenghua.yu@intel.com, thunder.leizhen@huawei.com, Hugh Dickins , feng.tang@intel.com, Jason Gunthorpe , Roman Gushchin , Thomas Gleixner , krisman@collabora.com, chris.hyser@oracle.com, Peter Collingbourne , "Eric W. Biederman" , Jens Axboe , legion@kernel.org, Rolf Eike Beer , Cyrill Gorcunov , Muchun Song , Viresh Kumar , Thomas Cedeno , sashal@kernel.org, cxfcosmos@gmail.com, Rasmus Villemoes , LKML , linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm , kernel-team , Pekka Enberg , Ingo Molnar , Oleg Nesterov , Jan Glauber , John Stultz , Rob Landley , Cyrill Gorcunov , "Serge E. Hallyn" , David Rientjes , Mel Gorman , Shaohua Li , Minchan Kim Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 2, 2021 at 4:18 PM Suren Baghdasaryan wrote: > > From: Colin Cross > > Refactor the madvise syscall to allow for parts of it to be reused by a > prctl syscall that affects vmas. > > Move the code that walks vmas in a virtual address range into a function > that takes a function pointer as a parameter. The only caller for now is > sys_madvise, which uses it to call madvise_vma_behavior on each vma, but > the next patch will add an additional caller. > > Move handling all vma behaviors inside madvise_behavior, and rename it to > madvise_vma_behavior. > > Move the code that updates the flags on a vma, including splitting or > merging the vma as necessary, into a new function called > madvise_update_vma. The next patch will add support for updating a new > anon_name field as well. > > Signed-off-by: Colin Cross > Cc: Pekka Enberg > Cc: Dave Hansen > Cc: Peter Zijlstra > Cc: Ingo Molnar > Cc: Oleg Nesterov > Cc: "Eric W. Biederman" > Cc: Jan Glauber > Cc: John Stultz > Cc: Rob Landley > Cc: Cyrill Gorcunov > Cc: Kees Cook > Cc: "Serge E. Hallyn" > Cc: David Rientjes > Cc: Al Viro > Cc: Hugh Dickins > Cc: Mel Gorman > Cc: Shaohua Li > Cc: Johannes Weiner > Cc: Minchan Kim > Signed-off-by: Andrew Morton > [sumits: rebased over v5.9-rc3] > Signed-off-by: Sumit Semwal > [surenb: rebased over v5.14-rc7] > Signed-off-by: Suren Baghdasaryan > --- > previous version including cover letter with test results is at: > https://lore.kernel.org/linux-mm/20210827191858.2037087-1-surenb@google.com/ > > changes in v9 > - Removed unnecessary initialization of 'error' to 0 in madvise_vma_behavior, > per Cyrill Gorcunov > - Replaced goto's with returns in madvise_vma_behavior, per Cyrill Gorcunov > - Recovered the comment explaining why we map ENOMEM to EAGAIN in > madvise_vma_behavior, per Cyrill Gorcunov > > mm/madvise.c | 317 +++++++++++++++++++++++++++------------------------ > 1 file changed, 170 insertions(+), 147 deletions(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index 56324a3dbc4e..54bf9f73f95d 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -63,76 +63,20 @@ static int madvise_need_mmap_write(int behavior) > } > > /* > - * We can potentially split a vm area into separate > - * areas, each area with its own behavior. > + * Update the vm_flags on regiion of a vma, splitting it or merging it as > + * necessary. Must be called with mmap_sem held for writing; > */ > -static long madvise_behavior(struct vm_area_struct *vma, > - struct vm_area_struct **prev, > - unsigned long start, unsigned long end, int behavior) > +static int madvise_update_vma(struct vm_area_struct *vma, > + struct vm_area_struct **prev, unsigned long start, > + unsigned long end, unsigned long new_flags) > { > struct mm_struct *mm = vma->vm_mm; > - int error = 0; > + int error; > pgoff_t pgoff; > - unsigned long new_flags = vma->vm_flags; > - > - switch (behavior) { > - case MADV_NORMAL: > - new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ; > - break; > - case MADV_SEQUENTIAL: > - new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ; > - break; > - case MADV_RANDOM: > - new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ; > - break; > - case MADV_DONTFORK: > - new_flags |= VM_DONTCOPY; > - break; > - case MADV_DOFORK: > - if (vma->vm_flags & VM_IO) { > - error = -EINVAL; > - goto out; > - } > - new_flags &= ~VM_DONTCOPY; > - break; > - case MADV_WIPEONFORK: > - /* MADV_WIPEONFORK is only supported on anonymous memory. */ > - if (vma->vm_file || vma->vm_flags & VM_SHARED) { > - error = -EINVAL; > - goto out; > - } > - new_flags |= VM_WIPEONFORK; > - break; > - case MADV_KEEPONFORK: > - new_flags &= ~VM_WIPEONFORK; > - break; > - case MADV_DONTDUMP: > - new_flags |= VM_DONTDUMP; > - break; > - case MADV_DODUMP: > - if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL) { > - error = -EINVAL; > - goto out; > - } > - new_flags &= ~VM_DONTDUMP; > - break; > - case MADV_MERGEABLE: > - case MADV_UNMERGEABLE: > - error = ksm_madvise(vma, start, end, behavior, &new_flags); > - if (error) > - goto out_convert_errno; > - break; > - case MADV_HUGEPAGE: > - case MADV_NOHUGEPAGE: > - error = hugepage_madvise(vma, &new_flags, behavior); > - if (error) > - goto out_convert_errno; > - break; > - } > > if (new_flags == vma->vm_flags) { > *prev = vma; > - goto out; > + return 0; > } > > pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); > @@ -149,21 +93,21 @@ static long madvise_behavior(struct vm_area_struct *vma, > if (start != vma->vm_start) { > if (unlikely(mm->map_count >= sysctl_max_map_count)) { > error = -ENOMEM; > - goto out; > + return error; Oh, I missed this one. Should be simply: - error = -ENOMEM; - goto out; + return -ENOMEM; > } > error = __split_vma(mm, vma, start, 1); > if (error) > - goto out_convert_errno; > + return error; > } > > if (end != vma->vm_end) { > if (unlikely(mm->map_count >= sysctl_max_map_count)) { > error = -ENOMEM; > - goto out; > + return error; same here. > } > error = __split_vma(mm, vma, end, 0); > if (error) > - goto out_convert_errno; > + return error; > } > > success: > @@ -172,15 +116,7 @@ static long madvise_behavior(struct vm_area_struct *vma, > */ > vma->vm_flags = new_flags; > > -out_convert_errno: > - /* > - * madvise() returns EAGAIN if kernel resources, such as > - * slab, are temporarily unavailable. > - */ > - if (error == -ENOMEM) > - error = -EAGAIN; > -out: > - return error; > + return 0; > } > > #ifdef CONFIG_SWAP > @@ -930,6 +866,94 @@ static long madvise_remove(struct vm_area_struct *vma, > return error; > } > > +/* > + * Apply an madvise behavior to a region of a vma. madvise_update_vma > + * will handle splitting a vm area into separate areas, each area with its own > + * behavior. > + */ > +static int madvise_vma_behavior(struct vm_area_struct *vma, > + struct vm_area_struct **prev, > + unsigned long start, unsigned long end, > + unsigned long behavior) > +{ > + int error; > + unsigned long new_flags = vma->vm_flags; > + > + switch (behavior) { > + case MADV_REMOVE: > + return madvise_remove(vma, prev, start, end); > + case MADV_WILLNEED: > + return madvise_willneed(vma, prev, start, end); > + case MADV_COLD: > + return madvise_cold(vma, prev, start, end); > + case MADV_PAGEOUT: > + return madvise_pageout(vma, prev, start, end); > + case MADV_FREE: > + case MADV_DONTNEED: > + return madvise_dontneed_free(vma, prev, start, end, behavior); > + case MADV_POPULATE_READ: > + case MADV_POPULATE_WRITE: > + return madvise_populate(vma, prev, start, end, behavior); > + case MADV_NORMAL: > + new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ; > + break; > + case MADV_SEQUENTIAL: > + new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ; > + break; > + case MADV_RANDOM: > + new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ; > + break; > + case MADV_DONTFORK: > + new_flags |= VM_DONTCOPY; > + break; > + case MADV_DOFORK: > + if (vma->vm_flags & VM_IO) > + return -EINVAL; > + new_flags &= ~VM_DONTCOPY; > + break; > + case MADV_WIPEONFORK: > + /* MADV_WIPEONFORK is only supported on anonymous memory. */ > + if (vma->vm_file || vma->vm_flags & VM_SHARED) > + return -EINVAL; > + new_flags |= VM_WIPEONFORK; > + break; > + case MADV_KEEPONFORK: > + new_flags &= ~VM_WIPEONFORK; > + break; > + case MADV_DONTDUMP: > + new_flags |= VM_DONTDUMP; > + break; > + case MADV_DODUMP: > + if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL) > + return -EINVAL; > + new_flags &= ~VM_DONTDUMP; > + break; > + case MADV_MERGEABLE: > + case MADV_UNMERGEABLE: > + error = ksm_madvise(vma, start, end, behavior, &new_flags); > + if (error) > + goto out; > + break; > + case MADV_HUGEPAGE: > + case MADV_NOHUGEPAGE: > + error = hugepage_madvise(vma, &new_flags, behavior); > + if (error) > + goto out; > + break; > + } > + > + error = madvise_update_vma(vma, prev, start, end, new_flags); > + > +out: > + /* > + * madvise() returns EAGAIN if kernel resources, such as > + * slab, are temporarily unavailable. > + */ > + if (error == -ENOMEM) > + error = -EAGAIN; > + return error; > +} > + > #ifdef CONFIG_MEMORY_FAILURE > /* > * Error injection support for memory error handling. > @@ -978,30 +1002,6 @@ static int madvise_inject_error(int behavior, > } > #endif > > -static long > -madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, > - unsigned long start, unsigned long end, int behavior) > -{ > - switch (behavior) { > - case MADV_REMOVE: > - return madvise_remove(vma, prev, start, end); > - case MADV_WILLNEED: > - return madvise_willneed(vma, prev, start, end); > - case MADV_COLD: > - return madvise_cold(vma, prev, start, end); > - case MADV_PAGEOUT: > - return madvise_pageout(vma, prev, start, end); > - case MADV_FREE: > - case MADV_DONTNEED: > - return madvise_dontneed_free(vma, prev, start, end, behavior); > - case MADV_POPULATE_READ: > - case MADV_POPULATE_WRITE: > - return madvise_populate(vma, prev, start, end, behavior); > - default: > - return madvise_behavior(vma, prev, start, end, behavior); > - } > -} > - > static bool > madvise_behavior_valid(int behavior) > { > @@ -1054,6 +1054,73 @@ process_madvise_behavior_valid(int behavior) > } > } > > +/* > + * Walk the vmas in range [start,end), and call the visit function on each one. > + * The visit function will get start and end parameters that cover the overlap > + * between the current vma and the original range. Any unmapped regions in the > + * original range will result in this function returning -ENOMEM while still > + * calling the visit function on all of the existing vmas in the range. > + * Must be called with the mmap_lock held for reading or writing. > + */ > +static > +int madvise_walk_vmas(struct mm_struct *mm, unsigned long start, > + unsigned long end, unsigned long arg, > + int (*visit)(struct vm_area_struct *vma, > + struct vm_area_struct **prev, unsigned long start, > + unsigned long end, unsigned long arg)) > +{ > + struct vm_area_struct *vma; > + struct vm_area_struct *prev; > + unsigned long tmp; > + int unmapped_error = 0; > + > + /* > + * If the interval [start,end) covers some unmapped address > + * ranges, just ignore them, but return -ENOMEM at the end. > + * - different from the way of handling in mlock etc. > + */ > + vma = find_vma_prev(mm, start, &prev); > + if (vma && start > vma->vm_start) > + prev = vma; > + > + for (;;) { > + int error; > + > + /* Still start < end. */ > + if (!vma) > + return -ENOMEM; > + > + /* Here start < (end|vma->vm_end). */ > + if (start < vma->vm_start) { > + unmapped_error = -ENOMEM; > + start = vma->vm_start; > + if (start >= end) > + break; > + } > + > + /* Here vma->vm_start <= start < (end|vma->vm_end) */ > + tmp = vma->vm_end; > + if (end < tmp) > + tmp = end; > + > + /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */ > + error = visit(vma, &prev, start, tmp, arg); > + if (error) > + return error; > + start = tmp; > + if (prev && start < prev->vm_end) > + start = prev->vm_end; > + if (start >= end) > + break; > + if (prev) > + vma = prev->vm_next; > + else /* madvise_remove dropped mmap_lock */ > + vma = find_vma(mm, start); > + } > + > + return unmapped_error; > +} > + > /* > * The madvise(2) system call. > * > @@ -1126,9 +1193,7 @@ process_madvise_behavior_valid(int behavior) > */ > int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior) > { > - unsigned long end, tmp; > - struct vm_area_struct *vma, *prev; > - int unmapped_error = 0; > + unsigned long end; > int error = -EINVAL; > int write; > size_t len; > @@ -1168,51 +1233,9 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh > mmap_read_lock(mm); > } > > - /* > - * If the interval [start,end) covers some unmapped address > - * ranges, just ignore them, but return -ENOMEM at the end. > - * - different from the way of handling in mlock etc. > - */ > - vma = find_vma_prev(mm, start, &prev); > - if (vma && start > vma->vm_start) > - prev = vma; > - > blk_start_plug(&plug); > - for (;;) { > - /* Still start < end. */ > - error = -ENOMEM; > - if (!vma) > - goto out; > - > - /* Here start < (end|vma->vm_end). */ > - if (start < vma->vm_start) { > - unmapped_error = -ENOMEM; > - start = vma->vm_start; > - if (start >= end) > - goto out; > - } > - > - /* Here vma->vm_start <= start < (end|vma->vm_end) */ > - tmp = vma->vm_end; > - if (end < tmp) > - tmp = end; > - > - /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */ > - error = madvise_vma(vma, &prev, start, tmp, behavior); > - if (error) > - goto out; > - start = tmp; > - if (prev && start < prev->vm_end) > - start = prev->vm_end; > - error = unmapped_error; > - if (start >= end) > - goto out; > - if (prev) > - vma = prev->vm_next; > - else /* madvise_remove dropped mmap_lock */ > - vma = find_vma(mm, start); > - } > -out: > + error = madvise_walk_vmas(mm, start, end, behavior, > + madvise_vma_behavior); > blk_finish_plug(&plug); > if (write) > mmap_write_unlock(mm); > -- > 2.33.0.153.gba50c8fa24-goog >