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 3F06EC433FE for ; Fri, 14 Jan 2022 22:05:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C13A76B00F1; Fri, 14 Jan 2022 17:05:58 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B9CE46B00F3; Fri, 14 Jan 2022 17:05:58 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9EE996B00F4; Fri, 14 Jan 2022 17:05:58 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0151.hostedemail.com [216.40.44.151]) by kanga.kvack.org (Postfix) with ESMTP id 850EF6B00F1 for ; Fri, 14 Jan 2022 17:05:58 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 497BA181F3B4A for ; Fri, 14 Jan 2022 22:05:58 +0000 (UTC) X-FDA: 79030275996.24.7FCD616 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf15.hostedemail.com (Postfix) with ESMTP id CC3F1A0007 for ; Fri, 14 Jan 2022 22:05:57 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1BAAD6200C; Fri, 14 Jan 2022 22:05:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9571C36AE9; Fri, 14 Jan 2022 22:05:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1642197956; bh=nrjO1l+ryFYU1dNFEZ+ygqUkzBGYKDsvKqXCEcGYS+8=; h=Date:From:To:Subject:In-Reply-To:From; b=j83QTi9u36yvVZt37MSRMtu+2c5TTNaONkTSX1jVpwuRN4+qehwOWnKZcHrulb/jP ZMC+zsBrwQlyhYEbGZyEq9XeDhKgKXRv1RLBDFPeZrjQpqvl8YymjPF0BtXIStjL6Z 0IXWe1KsqQCDE2Rk0//3EsODVLTQZ+0LndEd/dUc= Date: Fri, 14 Jan 2022 14:05:55 -0800 From: Andrew Morton To: akpm@linux-foundation.org, ccross@google.com, dave.hansen@intel.com, ebiederm@xmission.com, gorcunov@openvz.org, hannes@cmpxchg.org, hughd@google.com, jan.glauber@gmail.com, john.stultz@linaro.org, keescook@chromium.org, linux-mm@kvack.org, mgorman@suse.de, minchan@kernel.org, mingo@kernel.org, mm-commits@vger.kernel.org, oleg@redhat.com, penberg@kernel.org, peterz@infradead.org, rientjes@google.com, rob@landley.net, serge.hallyn@ubuntu.com, shli@fusionio.com, surenb@google.com, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk Subject: [patch 056/146] mm: rearrange madvise code to allow for reuse Message-ID: <20220114220555.kAbhSEmus%akpm@linux-foundation.org> In-Reply-To: <20220114140222.6b14f0061194d3200000c52d@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Stat-Signature: c8h6irjccs4fdgcq9mr81u9afckutj7z Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=j83QTi9u; dmarc=none; spf=pass (imf15.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: CC3F1A0007 X-HE-Tag: 1642197957-107295 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: From: Colin Cross Subject: mm: rearrange madvise code to allow for reuse Patch series "mm: rearrange madvise code to allow for reuse", v11. Speed up fork() by up to 40% by refcounting the anon vma name field. I checked the image sizes with allnoconfig builds: unpatched Linus' ToT text data bss dec hex filename 1324759 32 73928 1398719 1557bf vmlinux After the first patch is applied (madvise refactoring) text data bss dec hex filename 1322346 32 73928 1396306 154e52 vmlinux >>> 2413 bytes decrease vs ToT <<< After all patches applied with CONFIG_ANON_VMA_NAME=n text data bss dec hex filename 1322337 32 73928 1396297 154e49 vmlinux >>> 2422 bytes decrease vs ToT <<< After all patches applied with CONFIG_ANON_VMA_NAME=y text data bss dec hex filename 1325228 32 73928 1399188 155994 vmlinux >>> 469 bytes increase vs ToT <<< This patch (of 3): 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. Link: https://lkml.kernel.org/r/20211019215511.3771969-1-surenb@google.com Signed-off-by: Colin Cross Signed-off-by: Suren Baghdasaryan 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 --- mm/madvise.c | 338 +++++++++++++++++++++++++------------------------ 1 file changed, 178 insertions(+), 160 deletions(-) --- a/mm/madvise.c~mm-rearrange-madvise-code-to-allow-for-reuse +++ a/mm/madvise.c @@ -63,76 +63,20 @@ static int madvise_need_mmap_write(int b } /* - * We can potentially split a vm area into separate - * areas, each area with its own behavior. + * Update the vm_flags on region 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); @@ -147,23 +91,19 @@ static long madvise_behavior(struct vm_a *prev = vma; if (start != vma->vm_start) { - if (unlikely(mm->map_count >= sysctl_max_map_count)) { - error = -ENOMEM; - goto out; - } + if (unlikely(mm->map_count >= sysctl_max_map_count)) + 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; - } + if (unlikely(mm->map_count >= sysctl_max_map_count)) + return -ENOMEM; error = __split_vma(mm, vma, end, 0); if (error) - goto out_convert_errno; + return error; } success: @@ -172,15 +112,7 @@ success: */ 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 +862,94 @@ static long madvise_remove(struct vm_are 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 +998,6 @@ static int madvise_inject_error(int beha } #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) { @@ -1056,6 +1052,73 @@ process_madvise_behavior_valid(int behav } /* + * 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. * * Applications can use madvise() to advise the kernel how it should @@ -1127,10 +1190,8 @@ process_madvise_behavior_valid(int behav */ 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; - int error = -EINVAL; + unsigned long end; + int error; int write; size_t len; struct blk_plug plug; @@ -1138,23 +1199,22 @@ int do_madvise(struct mm_struct *mm, uns start = untagged_addr(start); if (!madvise_behavior_valid(behavior)) - return error; + return -EINVAL; if (!PAGE_ALIGNED(start)) - return error; + return -EINVAL; len = PAGE_ALIGN(len_in); /* Check to see whether len was rounded up from small -ve to zero */ if (len_in && !len) - return error; + return -EINVAL; end = start + len; if (end < start) - return error; + return -EINVAL; - error = 0; if (end == start) - return error; + return 0; #ifdef CONFIG_MEMORY_FAILURE if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE) @@ -1169,51 +1229,9 @@ int do_madvise(struct mm_struct *mm, uns 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); _