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s=arc-20220608; d=hostedemail.com; t=1706592017; a=rsa-sha256; cv=none; b=7EV2cbp5o1j8Qk4FVVCgwszlKFXhYJuVGjQWNi02ri9k6YTi/Bn8+4LQrml3/Nkxkl5iqu Do+jlWaiGARKlYgxEbpC8PnA69Gd7wixFijTcTM/6Mx2xB/qjvZXQjdXlwPp9qtZlyUpVS hf8D9cyZ+HdYrmdxLgVOXxt3SECgbBw= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=none; spf=pass (imf13.hostedemail.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com; dmarc=pass (policy=none) header.from=arm.com 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> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 6FF042000B X-Rspam-User: X-Stat-Signature: u1ci798wzhx68s45jnpbmabtcbzdpwc5 X-Rspamd-Server: rspam03 X-HE-Tag: 1706592017-259505 X-HE-Meta: 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 Ns4F5lJE FqQ7OIbztCZOF+KjMipAc0BwPft7+Rf7OsIToweYgJMDP0SMYSVtvivXI9N/aZY6KsD9cLutgwLhS3yF0mNFQPHa/c6d+Al5XtW2fhJnYhIuJG+3ntGcW4XHJLpa0m9Hc1ONtiDiGfwO49ZNPwev5eqMfNebn1sVZTrtbQW6GZ7i228Bw3+lc5kI9kGjsCw0N+WHpL2TAZMXDk4fRCpdKSUjssXZ7YCSDc7SC6yA06kX9C/wkGlr55Af2rEjor56cASkN 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: List-Subscribe: List-Unsubscribe: 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.