From patchwork Wed Dec 18 16:23:50 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Price X-Patchwork-Id: 11301283 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E9B8B14E3 for ; Wed, 18 Dec 2019 16:25:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A0BAF227BF for ; Wed, 18 Dec 2019 16:25:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A0BAF227BF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C6BB18E0127; Wed, 18 Dec 2019 11:24:58 -0500 (EST) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id C1A958E00F5; Wed, 18 Dec 2019 11:24:58 -0500 (EST) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AE4348E0127; Wed, 18 Dec 2019 11:24:58 -0500 (EST) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0040.hostedemail.com [216.40.44.40]) by kanga.kvack.org (Postfix) with ESMTP id 8B77C8E00F5 for ; Wed, 18 Dec 2019 11:24:58 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 4DF3C824934B for ; Wed, 18 Dec 2019 16:24:58 +0000 (UTC) X-FDA: 76278786276.21.quiet97_2b590aaf65b15 X-Spam-Summary: 2,0,0,632b167aa213cda9,d41d8cd98f00b204,steven.price@arm.com,:akpm@linux-foundation.org::steven.price@arm.com:luto@kernel.org:ard.biesheuvel@linaro.org:arnd@arndb.de:bp@alien8.de:catalin.marinas@arm.com:dave.hansen@linux.intel.com:mingo@redhat.com:james.morse@arm.com:jglisse@redhat.com:peterz@infradead.org:tglx@linutronix.de:will@kernel.org:x86@kernel.org:hpa@zytor.com:linux-arm-kernel@lists.infradead.org:linux-kernel@vger.kernel.org:mark.rutland@arm.com:kan.liang@linux.intel.com,RULES_HIT:1:2:41:69:355:379:541:800:960:968:973:988:989:1260:1261:1311:1314:1345:1359:1437:1515:1605:1730:1747:1777:1792:1801:2198:2199:2393:2553:2559:2562:2693:2730:2895:2898:3138:3139:3140:3141:3142:3865:3866:3867:3868:3871:3872:3874:4052:4250:4321:4605:5007:6117:6119:6261:6691:6742:6755:7875:7903:8634:8660:9036:9592:10004:11026:11658:11914:12043:12219:12291:12296:12297:12438:12517:12519:12555:12683:12895:13141:13148:13180:13229:13230:13894:14096:14394:21080:21451:21627:21972:21990: 30012:30 X-HE-Tag: quiet97_2b590aaf65b15 X-Filterd-Recvd-Size: 11764 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf18.hostedemail.com (Postfix) with ESMTP for ; Wed, 18 Dec 2019 16:24:57 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5113430E; Wed, 18 Dec 2019 08:24:57 -0800 (PST) Received: from e112269-lin.arm.com (e112269-lin.cambridge.arm.com [10.1.196.56]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A92CC3F719; Wed, 18 Dec 2019 08:24:54 -0800 (PST) From: Steven Price To: Andrew Morton , linux-mm@kvack.org Cc: Steven Price , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Dave Hansen , Ingo Molnar , James Morse , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Peter Zijlstra , Thomas Gleixner , Will Deacon , x86@kernel.org, "H. Peter Anvin" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Mark Rutland , "Liang, Kan" Subject: [PATCH v17 11/23] mm: pagewalk: Add p4d_entry() and pgd_entry() Date: Wed, 18 Dec 2019 16:23:50 +0000 Message-Id: <20191218162402.45610-12-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191218162402.45610-1-steven.price@arm.com> References: <20191218162402.45610-1-steven.price@arm.com> MIME-Version: 1.0 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: pgd_entry() and pud_entry() were removed by commit 0b1fbfe50006c410 ("mm/pagewalk: remove pgd_entry() and pud_entry()") because there were no users. We're about to add users so reintroduce them, along with p4d_entry() as we now have 5 levels of tables. Note that commit a00cc7d9dd93d66a ("mm, x86: add support for PUD-sized transparent hugepages") already re-added pud_entry() but with different semantics to the other callbacks. This commit reverts the semantics back to match the other callbacks. To support hmm.c which now uses the new semantics of pud_entry() a new member ('action') of struct mm_walk is added which allows the callbacks to either descend (ACTION_SUBTREE, the default), skip (ACTION_CONTINUE) or repeat the callback (ACTION_AGAIN). hmm.c is then updated to call pud_trans_huge_lock() itself and make use of the splitting/retry logic of the core code. After this change pud_entry() is called for all entries, not just transparent huge pages. Signed-off-by: Steven Price Reviewed-by: Thomas Hellstrom --- include/linux/pagewalk.h | 34 ++++++++++++++++++++----- mm/hmm.c | 55 ++++++++++++++++++++++------------------ mm/pagewalk.c | 50 +++++++++++++++++++++++++----------- 3 files changed, 94 insertions(+), 45 deletions(-) diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h index 6ec82e92c87f..aa6a0b63964e 100644 --- a/include/linux/pagewalk.h +++ b/include/linux/pagewalk.h @@ -8,15 +8,15 @@ struct mm_walk; /** * mm_walk_ops - callbacks for walk_page_range - * @pud_entry: if set, called for each non-empty PUD (2nd-level) entry - * this handler should only handle pud_trans_huge() puds. - * the pmd_entry or pte_entry callbacks will be used for - * regular PUDs. - * @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry + * @pgd_entry: if set, called for each non-empty PGD (top-level) entry + * @p4d_entry: if set, called for each non-empty P4D entry + * @pud_entry: if set, called for each non-empty PUD entry + * @pmd_entry: if set, called for each non-empty PMD entry * this handler is required to be able to handle * pmd_trans_huge() pmds. They may simply choose to * split_huge_page() instead of handling it explicitly. - * @pte_entry: if set, called for each non-empty PTE (4th-level) entry + * @pte_entry: if set, called for each non-empty PTE (lowest-level) + * entry * @pte_hole: if set, called for each hole at all levels * @hugetlb_entry: if set, called for each hugetlb entry * @test_walk: caller specific callback function to determine whether @@ -27,8 +27,15 @@ struct mm_walk; * @pre_vma: if set, called before starting walk on a non-null vma. * @post_vma: if set, called after a walk on a non-null vma, provided * that @pre_vma and the vma walk succeeded. + * + * p?d_entry callbacks are called even if those levels are folded on a + * particular architecture/configuration. */ struct mm_walk_ops { + int (*pgd_entry)(pgd_t *pgd, unsigned long addr, + unsigned long next, struct mm_walk *walk); + int (*p4d_entry)(p4d_t *p4d, unsigned long addr, + unsigned long next, struct mm_walk *walk); int (*pud_entry)(pud_t *pud, unsigned long addr, unsigned long next, struct mm_walk *walk); int (*pmd_entry)(pmd_t *pmd, unsigned long addr, @@ -47,11 +54,25 @@ struct mm_walk_ops { void (*post_vma)(struct mm_walk *walk); }; +/* + * Action for pud_entry / pmd_entry callbacks. + * ACTION_SUBTREE is the default + */ +enum page_walk_action { + /* Descend to next level, splitting huge pages if needed and possible */ + ACTION_SUBTREE = 0, + /* Continue to next entry at this level (ignoring any subtree) */ + ACTION_CONTINUE = 1, + /* Call again for this entry */ + ACTION_AGAIN = 2 +}; + /** * mm_walk - walk_page_range data * @ops: operation to call during the walk * @mm: mm_struct representing the target process of page table walk * @vma: vma currently walked (NULL if walking outside vmas) + * @action: next action to perform (see enum page_walk_action) * @private: private data for callbacks' usage * * (see the comment on walk_page_range() for more details) @@ -60,6 +81,7 @@ struct mm_walk { const struct mm_walk_ops *ops; struct mm_struct *mm; struct vm_area_struct *vma; + enum page_walk_action action; void *private; }; diff --git a/mm/hmm.c b/mm/hmm.c index d379cb6496ae..05241c82e05c 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -477,20 +477,30 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, unsigned long addr = start, next; pmd_t *pmdp; pud_t pud; - int ret; + int ret = 0; + spinlock_t *ptl = pud_trans_huge_lock(pudp, walk->vma); + + if (!ptl) + return 0; + + /* Normally we don't want to split the huge page */ + walk->action = ACTION_CONTINUE; -again: pud = READ_ONCE(*pudp); - if (pud_none(pud)) - return hmm_vma_walk_hole(start, end, walk); + if (pud_none(pud)) { + ret = hmm_vma_walk_hole(start, end, walk); + goto out_unlock; + } if (pud_huge(pud) && pud_devmap(pud)) { unsigned long i, npages, pfn; uint64_t *pfns, cpu_flags; bool fault, write_fault; - if (!pud_present(pud)) - return hmm_vma_walk_hole(start, end, walk); + if (!pud_present(pud)) { + ret = hmm_vma_walk_hole(start, end, walk); + goto out_unlock; + } i = (addr - range->start) >> PAGE_SHIFT; npages = (end - addr) >> PAGE_SHIFT; @@ -499,16 +509,20 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, cpu_flags = pud_to_hmm_pfn_flags(range, pud); hmm_range_need_fault(hmm_vma_walk, pfns, npages, cpu_flags, &fault, &write_fault); - if (fault || write_fault) - return hmm_vma_walk_hole_(addr, end, fault, - write_fault, walk); + if (fault || write_fault) { + ret = hmm_vma_walk_hole_(addr, end, fault, + write_fault, walk); + goto out_unlock; + } pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); for (i = 0; i < npages; ++i, ++pfn) { hmm_vma_walk->pgmap = get_dev_pagemap(pfn, hmm_vma_walk->pgmap); - if (unlikely(!hmm_vma_walk->pgmap)) - return -EBUSY; + if (unlikely(!hmm_vma_walk->pgmap)) { + ret = -EBUSY; + goto out_unlock; + } pfns[i] = hmm_device_entry_from_pfn(range, pfn) | cpu_flags; } @@ -517,22 +531,15 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, hmm_vma_walk->pgmap = NULL; } hmm_vma_walk->last = end; - return 0; + goto out_unlock; } - split_huge_pud(walk->vma, pudp, addr); - if (pud_none(*pudp)) - goto again; + /* Ask for the PUD to be split */ + walk->action = ACTION_SUBTREE; - pmdp = pmd_offset(pudp, addr); - do { - next = pmd_addr_end(addr, end); - ret = hmm_vma_walk_pmd(pmdp, addr, next, walk); - if (ret) - return ret; - } while (pmdp++, addr = next, addr != end); - - return 0; +out_unlock: + spin_unlock(ptl); + return ret; } #else #define hmm_vma_walk_pud NULL diff --git a/mm/pagewalk.c b/mm/pagewalk.c index ea0b9e606ad1..690af44609e2 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -46,6 +46,9 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, break; continue; } + + walk->action = ACTION_SUBTREE; + /* * This implies that each ->pmd_entry() handler * needs to know about pmd_trans_huge() pmds @@ -55,16 +58,21 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, if (err) break; + if (walk->action == ACTION_AGAIN) + goto again; + /* * Check this here so we only break down trans_huge * pages when we _need_ to */ - if (!ops->pte_entry) + if (walk->action == ACTION_CONTINUE || + !(ops->pte_entry)) continue; split_huge_pmd(walk->vma, pmd, addr); if (pmd_trans_unstable(pmd)) goto again; + err = walk_pte_range(pmd, addr, next, walk); if (err) break; @@ -93,24 +101,25 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, continue; } - if (ops->pud_entry) { - spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma); + walk->action = ACTION_SUBTREE; - if (ptl) { - err = ops->pud_entry(pud, addr, next, walk); - spin_unlock(ptl); - if (err) - break; - continue; - } - } + if (ops->pud_entry) + err = ops->pud_entry(pud, addr, next, walk); + if (err) + break; + + if (walk->action == ACTION_AGAIN) + goto again; + + if (walk->action == ACTION_CONTINUE || + !(ops->pmd_entry || ops->pte_entry)) + continue; split_huge_pud(walk->vma, pud, addr); if (pud_none(*pud)) goto again; - if (ops->pmd_entry || ops->pte_entry) - err = walk_pmd_range(pud, addr, next, walk); + err = walk_pmd_range(pud, addr, next, walk); if (err) break; } while (pud++, addr = next, addr != end); @@ -136,7 +145,12 @@ static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end, break; continue; } - if (ops->pmd_entry || ops->pte_entry) + if (ops->p4d_entry) { + err = ops->p4d_entry(p4d, addr, next, walk); + if (err) + break; + } + if (ops->pud_entry || ops->pmd_entry || ops->pte_entry) err = walk_pud_range(p4d, addr, next, walk); if (err) break; @@ -163,7 +177,13 @@ static int walk_pgd_range(unsigned long addr, unsigned long end, break; continue; } - if (ops->pmd_entry || ops->pte_entry) + if (ops->pgd_entry) { + err = ops->pgd_entry(pgd, addr, next, walk); + if (err) + break; + } + if (ops->p4d_entry || ops->pud_entry || ops->pmd_entry || + ops->pte_entry) err = walk_p4d_range(pgd, addr, next, walk); if (err) break;