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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1DA30C47DA9 for ; Tue, 30 Jan 2024 05:20:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To: Subject:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=YR6/mMg7O6ORRskwSkJYZzxTdncib0KG/nvpmsnlrKw=; b=S8EMiLquVLxbzk Y5OXbMA1b+bpZZ1yJQMqRdqydqIopcEYDF3toC6mfsodpnPSNIynYHPkivM2fqhpgHHZFG6xOYoBk +seJzKmS9/elZ63oqR2jfSHK1n1a6UtrZWB4DJFOlb7p8LODr0glIoAiv15HwBBYUPZwwd1vow/VC aqoElns3NaVdUic2XdnNdjmlmROAC7db4sCaArYY5jLEy3UkxgvYDejCdAigBcZaNyvJ6UJTDfTWE v45gHYy4zBPCQfbLULSSrISkHUksdmDX8EBuvrCgYchjM3xQF6tCab3XfMN3zmylSGGBKZ7BYBRm5 UlIAhBsrO68dTyQTCfUw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rUgXk-0000000FJVv-3d3s; Tue, 30 Jan 2024 05:20:20 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rUgXi-0000000FJVF-2Xy7 for linux-arm-kernel@lists.infradead.org; Tue, 30 Jan 2024 05:20:19 +0000 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 43296DA7; Mon, 29 Jan 2024 21:21:00 -0800 (PST) Received: from [10.163.41.110] (unknown [10.163.41.110]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A76F93F762; Mon, 29 Jan 2024 21:20:03 -0800 (PST) Message-ID: <61a3dbb7-25b6-4f49-aa70-9a8aaeb53365@arm.com> Date: Tue, 30 Jan 2024 10:50:00 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v3 08/35] mm: cma: Introduce cma_alloc_range() Content-Language: en-US To: Alexandru Elisei , catalin.marinas@arm.com, will@kernel.org, oliver.upton@linux.dev, maz@kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, arnd@arndb.de, akpm@linux-foundation.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, mhiramat@kernel.org, rppt@kernel.org, hughd@google.com Cc: pcc@google.com, steven.price@arm.com, vincenzo.frascino@arm.com, david@redhat.com, eugenis@google.com, kcc@google.com, hyesoo.yu@samsung.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org References: <20240125164256.4147-1-alexandru.elisei@arm.com> <20240125164256.4147-9-alexandru.elisei@arm.com> From: Anshuman Khandual In-Reply-To: <20240125164256.4147-9-alexandru.elisei@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240129_212018_754567_9E9CE45B X-CRM114-Status: GOOD ( 33.34 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 1/25/24 22:12, Alexandru Elisei wrote: > Today, cma_alloc() is used to allocate a contiguous memory region. The > function allows the caller to specify the number of pages to allocate, but > not the starting address. cma_alloc() will walk over the entire CMA region > trying to allocate the first available range of the specified size. > > Introduce cma_alloc_range(), which makes CMA more versatile by allowing the > caller to specify a particular range in the CMA region, defined by the > start pfn and the size. > > arm64 will make use of this function when tag storage management will be > implemented: cma_alloc_range() will be used to reserve the tag storage > associated with a tagged page. Basically, you would like to pass on a preferred start address and the allocation could just fail if a contig range is not available from such a starting address ? Then why not just change cma_alloc() to take a new argument 'start_pfn'. Why create a new but almost similar allocator ? But then I am wondering why this could not be done in the arm64 platform code itself operating on a CMA area reserved just for tag storage. Unless this new allocator has other usage beyond MTE, this could be implemented in the platform itself. > > Signed-off-by: Alexandru Elisei > --- > > Changes since rfc v2: > > * New patch. > > include/linux/cma.h | 2 + > include/trace/events/cma.h | 59 ++++++++++++++++++++++++++ > mm/cma.c | 86 ++++++++++++++++++++++++++++++++++++++ > 3 files changed, 147 insertions(+) > > diff --git a/include/linux/cma.h b/include/linux/cma.h > index 63873b93deaa..e32559da6942 100644 > --- a/include/linux/cma.h > +++ b/include/linux/cma.h > @@ -50,6 +50,8 @@ extern int cma_init_reserved_mem(phys_addr_t base, phys_addr_t size, > struct cma **res_cma); > extern struct page *cma_alloc(struct cma *cma, unsigned long count, unsigned int align, > bool no_warn); > +extern int cma_alloc_range(struct cma *cma, unsigned long start, unsigned long count, > + unsigned tries, gfp_t gfp); > extern bool cma_pages_valid(struct cma *cma, const struct page *pages, unsigned long count); > extern bool cma_release(struct cma *cma, const struct page *pages, unsigned long count); > > diff --git a/include/trace/events/cma.h b/include/trace/events/cma.h > index 25103e67737c..a89af313a572 100644 > --- a/include/trace/events/cma.h > +++ b/include/trace/events/cma.h > @@ -36,6 +36,65 @@ TRACE_EVENT(cma_release, > __entry->count) > ); > > +TRACE_EVENT(cma_alloc_range_start, > + > + TP_PROTO(const char *name, unsigned long start, unsigned long count, > + unsigned tries), > + > + TP_ARGS(name, start, count, tries), > + > + TP_STRUCT__entry( > + __string(name, name) > + __field(unsigned long, start) > + __field(unsigned long, count) > + __field(unsigned, tries) > + ), > + > + TP_fast_assign( > + __assign_str(name, name); > + __entry->start = start; > + __entry->count = count; > + __entry->tries = tries; > + ), > + > + TP_printk("name=%s start=%lx count=%lu tries=%u", > + __get_str(name), > + __entry->start, > + __entry->count, > + __entry->tries) > +); > + > +TRACE_EVENT(cma_alloc_range_finish, > + > + TP_PROTO(const char *name, unsigned long start, unsigned long count, > + unsigned attempts, int err), > + > + TP_ARGS(name, start, count, attempts, err), > + > + TP_STRUCT__entry( > + __string(name, name) > + __field(unsigned long, start) > + __field(unsigned long, count) > + __field(unsigned, attempts) > + __field(int, err) > + ), > + > + TP_fast_assign( > + __assign_str(name, name); > + __entry->start = start; > + __entry->count = count; > + __entry->attempts = attempts; > + __entry->err = err; > + ), > + > + TP_printk("name=%s start=%lx count=%lu attempts=%u err=%d", > + __get_str(name), > + __entry->start, > + __entry->count, > + __entry->attempts, > + __entry->err) > +); > + > TRACE_EVENT(cma_alloc_start, > > TP_PROTO(const char *name, unsigned long count, unsigned int align), > diff --git a/mm/cma.c b/mm/cma.c > index 543bb6b3be8e..4a0f68b9443b 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -416,6 +416,92 @@ static void cma_debug_show_areas(struct cma *cma) > static inline void cma_debug_show_areas(struct cma *cma) { } > #endif > > +/** > + * cma_alloc_range() - allocate pages in a specific range > + * @cma: Contiguous memory region for which the allocation is performed. > + * @start: Starting pfn of the allocation. > + * @count: Requested number of pages > + * @tries: Number of tries if the range is busy > + * @no_warn: Avoid printing message about failed allocation > + * > + * This function allocates part of contiguous memory from a specific contiguous > + * memory area, from the specified starting address. The 'start' pfn and the the > + * 'count' number of pages must be aligned to the CMA bitmap order per bit. > + */ > +int cma_alloc_range(struct cma *cma, unsigned long start, unsigned long count, > + unsigned tries, gfp_t gfp) > +{ > + unsigned long bitmap_maxno, bitmap_no, bitmap_start, bitmap_count; > + unsigned long i = 0; > + struct page *page; > + int err = -EINVAL; > + > + if (!cma || !cma->count || !cma->bitmap) > + goto out_stats; > + > + trace_cma_alloc_range_start(cma->name, start, count, tries); > + > + if (!count || start < cma->base_pfn || > + start + count > cma->base_pfn + cma->count) > + goto out_stats; > + > + if (!IS_ALIGNED(start | count, 1 << cma->order_per_bit)) > + goto out_stats; > + > + bitmap_start = (start - cma->base_pfn) >> cma->order_per_bit; > + bitmap_maxno = cma_bitmap_maxno(cma); > + bitmap_count = cma_bitmap_pages_to_bits(cma, count); > + > + spin_lock_irq(&cma->lock); > + bitmap_no = bitmap_find_next_zero_area(cma->bitmap, bitmap_maxno, > + bitmap_start, bitmap_count, 0); > + if (bitmap_no != bitmap_start) { > + spin_unlock_irq(&cma->lock); > + err = -EEXIST; > + goto out_stats; > + } > + bitmap_set(cma->bitmap, bitmap_start, bitmap_count); > + spin_unlock_irq(&cma->lock); > + > + for (i = 0; i < tries; i++) { > + mutex_lock(&cma_mutex); > + err = alloc_contig_range(start, start + count, MIGRATE_CMA, gfp); > + mutex_unlock(&cma_mutex); > + > + if (err != -EBUSY) > + break; > + } > + > + if (err) { > + cma_clear_bitmap(cma, start, count); > + } else { > + page = pfn_to_page(start); > + > + /* > + * CMA can allocate multiple page blocks, which results in > + * different blocks being marked with different tags. Reset the > + * tags to ignore those page blocks. > + */ > + for (i = 0; i < count; i++) > + page_kasan_tag_reset(nth_page(page, i)); > + } > + > +out_stats: > + trace_cma_alloc_range_finish(cma->name, start, count, i, err); > + > + if (err) { > + count_vm_events(CMA_ALLOC_FAIL, count); > + if (cma) > + cma_sysfs_account_fail_pages(cma, count); > + } else { > + count_vm_events(CMA_ALLOC_SUCCESS, count); > + cma_sysfs_account_success_pages(cma, count); > + } > + > + return err; > +} > + > + > /** > * cma_alloc() - allocate pages from contiguous area > * @cma: Contiguous memory region for which the allocation is performed. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel