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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: SRy17DoTzeQhc6cw6PKewWHYxFrDYyH2qFSLZbiDmXMZ62pWYUxjRMLd5Bwnpfj+K9yQZgwJzzcgjdurQz934EZ+M95HN8HCAmgcIdH7YDPt9w1KCXk4oI6YDxLrkDsZP/HwYnue5HC8u3wsOTB67QuLkRZjgm/ztlnIEA8hHaFU5XqCihnkpYULY3t+DAWZLbd3zZ1GjIHWEqewhCrn69fNubKiJE56RVYMED00cSNUf0Ncdp3GpGroPaXvYJ9gugsKX/A0KxNoUgdCQZL+6Cu+8MytAxarrY8QuT1zud/2YBlmPBt224pt5nYjyBcPnCzvBxosfKdQiuhrDOEC6Lu2Z1MI4pBHVp9svGhl0WgC8jqYpSx/blNTXtjL8a1fy2czwTQjp98ZfeNRwLl/3hOmfJV3VmOaaaDJyB1L+j1Nok76LwXN18uQ3KPWkn8q X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 31 Mar 2026 13:53:24.2287 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 35a9ba70-a3ac-4bcb-a2bc-08de8f2ce0a2 X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[4.158.2.129];Helo=[outbound-uk1.az.dlp.m.darktrace.com] X-MS-Exchange-CrossTenant-AuthSource: DU2PEPF00028D13.eurprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB4PR08MB10343 On 30/03/2026 3:33 pm, David Hildenbrand (Arm) wrote: >> >> +static void free_prepared_contig_range(struct page *page, >> + unsigned long nr_pages) > > Prefer two-tab indent in MM land. > >> +{ >> + while (nr_pages) { >> + unsigned int order; >> + unsigned long pfn; >> + >> + pfn = page_to_pfn(page); > > I'd just do above > > const unsigned long pfn = page_to_pfn(page); > unsigned long order; > >> + /* We are limited by the largest buddy order. */ >> + order = pfn ? __ffs(pfn) : MAX_PAGE_ORDER; >> + /* Don't exceed the number of pages to free. */ >> + order = min_t(unsigned int, order, ilog2(nr_pages)); >> + order = min_t(unsigned int, order, MAX_PAGE_ORDER); >> + >> + /* >> + * Free the chunk as a single block. Our caller has already >> + * called free_pages_prepare() for each order-0 page. >> + */ >> + __free_frozen_pages(page, order, FPI_PREPARED); >> + >> + page += 1UL << order; >> + nr_pages -= 1UL << order; >> + } >> +} >> + >> +static void __free_contig_range_common(unsigned long pfn, unsigned long nr_pages, >> + bool is_frozen) > > Dito. > >> +{ >> + struct page *page = pfn_to_page(pfn); >> + struct page *start = NULL; >> + unsigned long start_sec; >> + bool can_free = true; >> + unsigned long i; >> + >> + /* >> + * Contiguous PFNs might not have a contiguous "struct pages" in some >> + * kernel config. Therefore, check memdesc_section(), and stop batching >> + * once it changes, see num_pages_contiguous(). >> + */ >> + for (i = 0; i < nr_pages; i++, page++) { > > As Vlasta says, page++ needs a thought. (you have to redo the > pfn_to_page with the next pfn in case the section changes). It'll be fixed in the next version along with other mentioned nits. > >> + VM_WARN_ON_ONCE(PageHead(page)); >> + VM_WARN_ON_ONCE(PageTail(page)); >> + >> + if (!is_frozen) >> + can_free = put_page_testzero(page); >> + >> + if (can_free) >> + can_free = free_pages_prepare(page, 0); >> + >> + if (!can_free) { >> + if (start) { >> + free_prepared_contig_range(start, page - start); >> + start = NULL; >> + } >> + continue; >> + } >> + >> + if (start && memdesc_section(page->flags) != start_sec) { >> + free_prepared_contig_range(start, page - start); >> + start = page; >> + start_sec = memdesc_section(page->flags); >> + } else if (!start) { >> + start = page; >> + start_sec = memdesc_section(page->flags); >> + } >> + } >> + >> + if (start) >> + free_prepared_contig_range(start, page - start); >> +} >> + >> +/** >> + * __free_contig_range - Free contiguous range of order-0 pages. >> + * @pfn: Page frame number of the first page in the range. >> + * @nr_pages: Number of pages to free. >> + * >> + * For each order-0 struct page in the physically contiguous range, put a >> + * reference. Free any page who's reference count falls to zero. The >> + * implementation is functionally equivalent to, but significantly faster than >> + * calling __free_page() for each struct page in a loop. >> + * >> + * Memory allocated with alloc_pages(order>=1) then subsequently split to >> + * order-0 with split_page() is an example of appropriate contiguous pages that >> + * can be freed with this API. >> + * >> + * Context: May be called in interrupt context or while holding a normal >> + * spinlock, but not in NMI context or while holding a raw spinlock. > > Interesting that we didn't have a cond_resched() somewhere in there. > > -- --- Thanks, Usama