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 X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E65CC33CA9 for ; Mon, 13 Jan 2020 18:23:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5E282075B for ; Mon, 13 Jan 2020 18:23:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="nOHgIXNY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728811AbgAMSXB (ORCPT ); Mon, 13 Jan 2020 13:23:01 -0500 Received: from mail-wm1-f66.google.com ([209.85.128.66]:54154 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728633AbgAMSW7 (ORCPT ); Mon, 13 Jan 2020 13:22:59 -0500 Received: by mail-wm1-f66.google.com with SMTP id m24so10845614wmc.3; Mon, 13 Jan 2020 10:22:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to; bh=HvtNipEFRvSqP3jaFfF+/gzI7x9srFsAsvwnNexCPMc=; b=nOHgIXNYeLFlLcv0Fue8Gotajx+Py8tA/okmELVAncD7GUCeDe5V09UonLz2xSctXU 7si/5XixaR2TvwewBS73rb5PmMe4cs5H7pJBhfske3AVX8tyv+2kUNHZ18MfjV0mtW/K Jw+LQ36CaKPWgbOanQfM+f8+PrC7sGM3NMUzx1Q9DtFpsF62AWd77IH4H4LjsDrLb6Rq vGDGC2KwYmKhGnC3b4uhQVmxiolQ2+P+W7qAw3utEwEwcJE852c0UKpDZNJN6hKR+iCb CSvEBfj3wS1IBxW8dt43cOWssAg0wq0kCP6Bv+OfgnNMysBeq6F3py27cZEk9TMDPtu8 NcoA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to; bh=HvtNipEFRvSqP3jaFfF+/gzI7x9srFsAsvwnNexCPMc=; b=fTzt80l5iqPOxVhDO08v5zO9pCcTRNbMZcSJmISQ9YxluFJlzLPkzR6Dw4C7H47d/a LhjIxsDmd3CIC+Jn++vJIc95hYW/H6hv+gji7L09BoDswmwZGMWkJ6CAlgK4PKDuCX65 HOpDG1RIARr99n33p1hxbtHHmsx9CFSx2gPyIWoerB/sggqwIhwd37Rsw9ArYM7rrP1G fYVHyZ/DrLeJh3Ux1pZB8IXfgr94Am8C4ypclhz74M6YDkxrobvAGOqJtdSAli+EZRAg JDzRClUacYl3EaC8W28LISIAa+Cm+P/XJ6Ev1BmxP62c9l2KAFOV0LxosQK3JWDfDjlA 2erQ== X-Gm-Message-State: APjAAAVYNtszgYFTsLM4Wn9Scuu6GUdyu5dKPE3smkzyXhYtLWCVG5yg 8+ssnR3ORqfrPeybUfWAJVk= X-Google-Smtp-Source: APXvYqxbJXaeJAkyiPwUvQZXmSaI4fr5dpfHpmQFKjKeS0kg9B4Eph7t9CzIDCbzgj3EYt3LgqrSgA== X-Received: by 2002:a1c:6308:: with SMTP id x8mr21892071wmb.80.1578939777017; Mon, 13 Jan 2020 10:22:57 -0800 (PST) Received: from localhost.localdomain ([2a02:2450:10d2:194d:b860:a52e:b647:77fe]) by smtp.gmail.com with ESMTPSA id c2sm16021893wrp.46.2020.01.13.10.22.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Jan 2020 10:22:56 -0800 (PST) From: SeongJae Park To: Minchan Kim Cc: SeongJae Park , Andrew Morton , LKML , linux-mm , linux-api@vger.kernel.org, oleksandr@redhat.com, Suren Baghdasaryan , Tim Murray , Daniel Colascione , Sandeep Patil , Sonny Rao , Brian Geffon , Michal Hocko , Johannes Weiner , Shakeel Butt , John Dias Subject: Re: Re: [PATCH 1/4] mm: factor out madvise's core functionality Date: Mon, 13 Jan 2020 19:22:45 +0100 Message-Id: <20200113182245.30455-1-sj38.park@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200113181118.GB110363@google.com> (raw) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 13 Jan 2020 10:11:18 -0800 Minchan Kim wrote: > On Sat, Jan 11, 2020 at 08:37:37AM +0100, SeongJae Park wrote: > > On Fri, 10 Jan 2020 13:34:30 -0800 Minchan Kim wrote: > > > > > This patch factor out madvise's core functionality so that upcoming > > > patch can reuse it without duplication. It shouldn't change any behavior. > > > > > > Signed-off-by: Minchan Kim > > > --- > > > mm/madvise.c | 194 +++++++++++++++++++++++++++++---------------------- > > > 1 file changed, 111 insertions(+), 83 deletions(-) > > > > > > diff --git a/mm/madvise.c b/mm/madvise.c > > > index bcdb6a042787..0c901de531e4 100644 > > > --- a/mm/madvise.c > > > +++ b/mm/madvise.c > > > @@ -35,6 +35,7 @@ > > > struct madvise_walk_private { > > > struct mmu_gather *tlb; > > > bool pageout; > > > + struct task_struct *task; > > > }; > > > > > > /* > > > @@ -306,12 +307,13 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd, > > > bool pageout = private->pageout; > > > struct mm_struct *mm = tlb->mm; > > > struct vm_area_struct *vma = walk->vma; > > > + struct task_struct *task = private->task; > > > pte_t *orig_pte, *pte, ptent; > > > spinlock_t *ptl; > > > struct page *page = NULL; > > > LIST_HEAD(page_list); > > > > > > - if (fatal_signal_pending(current)) > > > + if (fatal_signal_pending(task)) > > > return -EINTR; > > > > > > #ifdef CONFIG_TRANSPARENT_HUGEPAGE > > > @@ -469,12 +471,14 @@ static const struct mm_walk_ops cold_walk_ops = { > > > }; > > > > > > static void madvise_cold_page_range(struct mmu_gather *tlb, > > > + struct task_struct *task, > > > struct vm_area_struct *vma, > > > unsigned long addr, unsigned long end) > > > { > > > struct madvise_walk_private walk_private = { > > > .pageout = false, > > > .tlb = tlb, > > > + .task = task, > > > }; > > > > > > tlb_start_vma(tlb, vma); > > > @@ -482,7 +486,7 @@ static void madvise_cold_page_range(struct mmu_gather *tlb, > > > tlb_end_vma(tlb, vma); > > > } > > > > > > -static long madvise_cold(struct vm_area_struct *vma, > > > +static long madvise_cold(struct task_struct *task, struct vm_area_struct *vma, > > > struct vm_area_struct **prev, > > > unsigned long start_addr, unsigned long end_addr) > > > { > > > @@ -495,19 +499,21 @@ static long madvise_cold(struct vm_area_struct *vma, > > > > > > lru_add_drain(); > > > tlb_gather_mmu(&tlb, mm, start_addr, end_addr); > > > - madvise_cold_page_range(&tlb, vma, start_addr, end_addr); > > > + madvise_cold_page_range(&tlb, task, vma, start_addr, end_addr); > > > tlb_finish_mmu(&tlb, start_addr, end_addr); > > > > > > return 0; > > > } > > > > > > static void madvise_pageout_page_range(struct mmu_gather *tlb, > > > + struct task_struct *task, > > > struct vm_area_struct *vma, > > > unsigned long addr, unsigned long end) > > > { > > > struct madvise_walk_private walk_private = { > > > .pageout = true, > > > .tlb = tlb, > > > + .task = task, > > > }; > > > > > > tlb_start_vma(tlb, vma); > > > @@ -531,9 +537,9 @@ static inline bool can_do_pageout(struct vm_area_struct *vma) > > > inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0; > > > } > > > > > > -static long madvise_pageout(struct vm_area_struct *vma, > > > - struct vm_area_struct **prev, > > > - unsigned long start_addr, unsigned long end_addr) > > > +static long madvise_pageout(struct task_struct *task, > > > + struct vm_area_struct *vma, struct vm_area_struct **prev, > > > + unsigned long start_addr, unsigned long end_addr) > > > { > > > struct mm_struct *mm = vma->vm_mm; > > > struct mmu_gather tlb; > > > @@ -547,7 +553,7 @@ static long madvise_pageout(struct vm_area_struct *vma, > > > > > > lru_add_drain(); > > > tlb_gather_mmu(&tlb, mm, start_addr, end_addr); > > > - madvise_pageout_page_range(&tlb, vma, start_addr, end_addr); > > > + madvise_pageout_page_range(&tlb, task, vma, start_addr, end_addr); > > > tlb_finish_mmu(&tlb, start_addr, end_addr); > > > > > > return 0; > > > @@ -751,7 +757,8 @@ static long madvise_dontneed_single_vma(struct vm_area_struct *vma, > > > return 0; > > > } > > > > > > -static long madvise_dontneed_free(struct vm_area_struct *vma, > > > +static long madvise_dontneed_free(struct mm_struct *mm, > > > + struct vm_area_struct *vma, > > > struct vm_area_struct **prev, > > > unsigned long start, unsigned long end, > > > int behavior) > > > @@ -763,8 +770,8 @@ static long madvise_dontneed_free(struct vm_area_struct *vma, > > > if (!userfaultfd_remove(vma, start, end)) { > > > *prev = NULL; /* mmap_sem has been dropped, prev is stale */ > > > > > > - down_read(¤t->mm->mmap_sem); > > > - vma = find_vma(current->mm, start); > > > + down_read(&mm->mmap_sem); > > > + vma = find_vma(mm, start); > > > if (!vma) > > > return -ENOMEM; > > > if (start < vma->vm_start) { > > > @@ -811,7 +818,8 @@ static long madvise_dontneed_free(struct vm_area_struct *vma, > > > * Application wants to free up the pages and associated backing store. > > > * This is effectively punching a hole into the middle of a file. > > > */ > > > -static long madvise_remove(struct vm_area_struct *vma, > > > +static long madvise_remove(struct mm_struct *mm, > > > + struct vm_area_struct *vma, > > > struct vm_area_struct **prev, > > > unsigned long start, unsigned long end) > > > { > > > @@ -845,13 +853,13 @@ static long madvise_remove(struct vm_area_struct *vma, > > > get_file(f); > > > if (userfaultfd_remove(vma, start, end)) { > > > /* mmap_sem was not released by userfaultfd_remove() */ > > > - up_read(¤t->mm->mmap_sem); > > > + up_read(&mm->mmap_sem); > > > } > > > error = vfs_fallocate(f, > > > FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, > > > offset, end - start); > > > fput(f); > > > - down_read(¤t->mm->mmap_sem); > > > + down_read(&mm->mmap_sem); > > > return error; > > > } > > > > > > @@ -925,21 +933,23 @@ static int madvise_inject_error(int behavior, > > > #endif > > > > > > static long > > > -madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, > > > +madvise_vma(struct task_struct *task, struct mm_struct *mm, > > > + 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); > > > + return madvise_remove(mm, vma, prev, start, end); > > > case MADV_WILLNEED: > > > return madvise_willneed(vma, prev, start, end); > > > case MADV_COLD: > > > - return madvise_cold(vma, prev, start, end); > > > + return madvise_cold(task, vma, prev, start, end); > > > case MADV_PAGEOUT: > > > - return madvise_pageout(vma, prev, start, end); > > > + return madvise_pageout(task, vma, prev, start, end); > > > case MADV_FREE: > > > case MADV_DONTNEED: > > > - return madvise_dontneed_free(vma, prev, start, end, behavior); > > > + return madvise_dontneed_free(mm, vma, prev, start, > > > + end, behavior); > > > default: > > > return madvise_behavior(vma, prev, start, end, behavior); > > > } > > > @@ -984,67 +994,19 @@ madvise_behavior_valid(int behavior) > > > } > > > > > > /* > > > - * The madvise(2) system call. > > > + * madvise_common - request behavior hint to address range of the target process > > > * > > > - * Applications can use madvise() to advise the kernel how it should > > > - * handle paging I/O in this VM area. The idea is to help the kernel > > > - * use appropriate read-ahead and caching techniques. The information > > > - * provided is advisory only, and can be safely disregarded by the > > > - * kernel without affecting the correct operation of the application. > > > + * @task: task_struct got behavior hint, not giving the hint > > > + * @mm: mm_struct got behavior hint, not giving the hint > > > + * @start: base address of the hinted range > > > + * @len_in: length of the hinted range > > > + * @behavior: requested hint > > > * > > > - * behavior values: > > > - * MADV_NORMAL - the default behavior is to read clusters. This > > > - * results in some read-ahead and read-behind. > > > - * MADV_RANDOM - the system should read the minimum amount of data > > > - * on any access, since it is unlikely that the appli- > > > - * cation will need more than what it asks for. > > > - * MADV_SEQUENTIAL - pages in the given range will probably be accessed > > > - * once, so they can be aggressively read ahead, and > > > - * can be freed soon after they are accessed. > > > - * MADV_WILLNEED - the application is notifying the system to read > > > - * some pages ahead. > > > - * MADV_DONTNEED - the application is finished with the given range, > > > - * so the kernel can free resources associated with it. > > > - * MADV_FREE - the application marks pages in the given range as lazy free, > > > - * where actual purges are postponed until memory pressure happens. > > > - * MADV_REMOVE - the application wants to free up the given range of > > > - * pages and associated backing store. > > > - * MADV_DONTFORK - omit this area from child's address space when forking: > > > - * typically, to avoid COWing pages pinned by get_user_pages(). > > > - * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking. > > > - * MADV_WIPEONFORK - present the child process with zero-filled memory in this > > > - * range after a fork. > > > - * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK > > > - * MADV_HWPOISON - trigger memory error handler as if the given memory range > > > - * were corrupted by unrecoverable hardware memory failure. > > > - * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory. > > > - * MADV_MERGEABLE - the application recommends that KSM try to merge pages in > > > - * this area with pages of identical content from other such areas. > > > - * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others. > > > - * MADV_HUGEPAGE - the application wants to back the given range by transparent > > > - * huge pages in the future. Existing pages might be coalesced and > > > - * new pages might be allocated as THP. > > > - * MADV_NOHUGEPAGE - mark the given range as not worth being backed by > > > - * transparent huge pages so the existing pages will not be > > > - * coalesced into THP and new pages will not be allocated as THP. > > > - * MADV_DONTDUMP - the application wants to prevent pages in the given range > > > - * from being included in its core dump. > > > - * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump. > > > - * > > > - * return values: > > > - * zero - success > > > - * -EINVAL - start + len < 0, start is not page-aligned, > > > - * "behavior" is not a valid value, or application > > > - * is attempting to release locked or shared pages, > > > - * or the specified address range includes file, Huge TLB, > > > - * MAP_SHARED or VMPFNMAP range. > > > - * -ENOMEM - addresses in the specified range are not currently > > > - * mapped, or are outside the AS of the process. > > > - * -EIO - an I/O error occurred while paging in data. > > > - * -EBADF - map exists, but area maps something that isn't a file. > > > - * -EAGAIN - a kernel resource was temporarily unavailable. > > > + * @task could be a zombie leader if it calls sys_exit so accessing mm_struct > > > + * via task->mm is prohibited. Please use @mm instead of task->mm. > > > */ > > > -SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) > > > +static int madvise_common(struct task_struct *task, struct mm_struct *mm, > > > + unsigned long start, size_t len_in, int behavior) > > > { > > > unsigned long end, tmp; > > > struct vm_area_struct *vma, *prev; > > > @@ -1082,10 +1044,10 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) > > > > > > write = madvise_need_mmap_write(behavior); > > > if (write) { > > > - if (down_write_killable(¤t->mm->mmap_sem)) > > > + if (down_write_killable(&mm->mmap_sem)) > > > return -EINTR; > > > } else { > > > - down_read(¤t->mm->mmap_sem); > > > + down_read(&mm->mmap_sem); > > > } > > > > > > /* > > > @@ -1093,7 +1055,7 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) > > > * ranges, just ignore them, but return -ENOMEM at the end. > > > * - different from the way of handling in mlock etc. > > > */ > > > - vma = find_vma_prev(current->mm, start, &prev); > > > + vma = find_vma_prev(mm, start, &prev); > > > if (vma && start > vma->vm_start) > > > prev = vma; > > > > > > @@ -1118,7 +1080,7 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) > > > tmp = end; > > > > > > /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */ > > > - error = madvise_vma(vma, &prev, start, tmp, behavior); > > > + error = madvise_vma(task, mm, vma, &prev, start, tmp, behavior); > > > if (error) > > > goto out; > > > start = tmp; > > > @@ -1130,14 +1092,80 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) > > > if (prev) > > > vma = prev->vm_next; > > > else /* madvise_remove dropped mmap_sem */ > > > - vma = find_vma(current->mm, start); > > > + vma = find_vma(mm, start); > > > } > > > out: > > > blk_finish_plug(&plug); > > > if (write) > > > - up_write(¤t->mm->mmap_sem); > > > + up_write(&mm->mmap_sem); > > > else > > > - up_read(¤t->mm->mmap_sem); > > > + up_read(&mm->mmap_sem); > > > > > > return error; > > > } > > > + > > > +/* > > > + * The madvise(2) system call. > > > + * > > > + * Applications can use madvise() to advise the kernel how it should > > > + * handle paging I/O in this VM area. The idea is to help the kernel > > > + * use appropriate read-ahead and caching techniques. The information > > > + * provided is advisory only, and can be safely disregarded by the > > > + * kernel without affecting the correct operation of the application. > > > + * > > > + * behavior values: > > > + * MADV_NORMAL - the default behavior is to read clusters. This > > > + * results in some read-ahead and read-behind. > > > + * MADV_RANDOM - the system should read the minimum amount of data > > > + * on any access, since it is unlikely that the appli- > > > + * cation will need more than what it asks for. > > > + * MADV_SEQUENTIAL - pages in the given range will probably be accessed > > > + * once, so they can be aggressively read ahead, and > > > + * can be freed soon after they are accessed. > > > + * MADV_WILLNEED - the application is notifying the system to read > > > + * some pages ahead. > > > + * MADV_DONTNEED - the application is finished with the given range, > > > + * so the kernel can free resources associated with it. > > > + * MADV_FREE - the application marks pages in the given range as lazy free, > > > + * where actual purges are postponed until memory pressure happens. > > > + * MADV_REMOVE - the application wants to free up the given range of > > > + * pages and associated backing store. > > > + * MADV_DONTFORK - omit this area from child's address space when forking: > > > + * typically, to avoid COWing pages pinned by get_user_pages(). > > > + * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking. > > > + * MADV_WIPEONFORK - present the child process with zero-filled memory in this > > > + * range after a fork. > > > + * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK > > > + * MADV_HWPOISON - trigger memory error handler as if the given memory range > > > + * were corrupted by unrecoverable hardware memory failure. > > > + * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory. > > > + * MADV_MERGEABLE - the application recommends that KSM try to merge pages in > > > + * this area with pages of identical content from other such areas. > > > + * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others. > > > + * MADV_HUGEPAGE - the application wants to back the given range by transparent > > > + * huge pages in the future. Existing pages might be coalesced and > > > + * new pages might be allocated as THP. > > > + * MADV_NOHUGEPAGE - mark the given range as not worth being backed by > > > + * transparent huge pages so the existing pages will not be > > > + * coalesced into THP and new pages will not be allocated as THP. > > > + * MADV_DONTDUMP - the application wants to prevent pages in the given range > > > + * from being included in its core dump. > > > + * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump. > > > > Just a trivial suggestion. How about adding brief descriptions for the > > 'MADV_COLD' and 'MADV_PAGEOUT' here, probably with another patch? > > How about this? > Feel free to suggest better wording. > > diff --git a/mm/madvise.c b/mm/madvise.c > index 3aa9aec6bfd9..78b3ab789486 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -1169,6 +1169,10 @@ static int madvise_common(struct task_struct *task, struct mm_struct *mm, > * MADV_DONTDUMP - the application wants to prevent pages in the given range > * from being included in its core dump. > * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump. > + * MADV_COLD - the application uses the memory less so the kernel can deactivate > + * the memory to evict them quickly when the memory pressure happen. > + * MADV_PAGEOUT - the application uses the memroy very rarely so kernel can > + * page out the memory instantly. Looks good to me :) Thanks, SeongJae Park > * > * return values: > * zero - success > > Thanks. >