Hi, On Tue, Jan 30, 2024 at 02:48:53PM +0530, Anshuman Khandual wrote: > > > On 1/25/24 22:12, Alexandru Elisei wrote: > > If the pages to be allocated are free, take them directly off the buddy > > allocator, instead of going through alloc_contig_range() and avoiding > > costly calls to lru_cache_disable(). > > > > Only allocations of the same size as the CMA region order are considered, > > to avoid taking the zone spinlock for too long. > > > > Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx> > > This patch seems to be improving standard cma_alloc() as well as > the previously added new allocator i.e cma_alloc_range() - via a > new helper cma_alloc_pages_fastpath(). Yes, that's correct. > > Should not any standard cma_alloc() improvement be discussed as > an independent patch separately irrespective of this series. OR > it is some how related to this series which I might be missing ? Yes, it's related to this series. I wrote this patch because it fixes a performance regression with Chrome when dynamic tag storage management is enabled [1]. I will bring back the commit message explaining that. [1] https://lore.kernel.org/linux-fsdevel/20231119165721.9849-27-alexandru.elisei@xxxxxxx/ Thanks, Alex > > > --- > > > > Changes since rfc v2: > > > > * New patch. Reworked from the rfc v2 patch #26 ("arm64: mte: Fast track > > reserving tag storage when the block is free") (David Hildenbrand). > > > > include/linux/page-flags.h | 15 ++++++++++++-- > > mm/Kconfig | 5 +++++ > > mm/cma.c | 42 ++++++++++++++++++++++++++++++++++---- > > mm/memory-failure.c | 8 ++++---- > > mm/page_alloc.c | 23 ++++++++++++--------- > > 5 files changed, 73 insertions(+), 20 deletions(-) > > > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > > index 735cddc13d20..b7237bce7446 100644 > > --- a/include/linux/page-flags.h > > +++ b/include/linux/page-flags.h > > @@ -575,11 +575,22 @@ TESTSCFLAG(HWPoison, hwpoison, PF_ANY) > > #define MAGIC_HWPOISON 0x48575053U /* HWPS */ > > extern void SetPageHWPoisonTakenOff(struct page *page); > > extern void ClearPageHWPoisonTakenOff(struct page *page); > > -extern bool take_page_off_buddy(struct page *page); > > -extern bool put_page_back_buddy(struct page *page); > > +extern bool PageHWPoisonTakenOff(struct page *page); > > #else > > PAGEFLAG_FALSE(HWPoison, hwpoison) > > +TESTSCFLAG_FALSE(HWPoison, hwpoison) > > #define __PG_HWPOISON 0 > > +static inline void SetPageHWPoisonTakenOff(struct page *page) { } > > +static inline void ClearPageHWPoisonTakenOff(struct page *page) { } > > +static inline bool PageHWPoisonTakenOff(struct page *page) > > +{ > > + return false; > > +} > > +#endif > > + > > +#ifdef CONFIG_WANTS_TAKE_PAGE_OFF_BUDDY > > +extern bool take_page_off_buddy(struct page *page, bool poison); > > +extern bool put_page_back_buddy(struct page *page, bool unpoison); > > #endif > > > > #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT) > > diff --git a/mm/Kconfig b/mm/Kconfig > > index ffc3a2ba3a8c..341cf53898db 100644 > > --- a/mm/Kconfig > > +++ b/mm/Kconfig > > @@ -745,12 +745,16 @@ config DEFAULT_MMAP_MIN_ADDR > > config ARCH_SUPPORTS_MEMORY_FAILURE > > bool > > > > +config WANTS_TAKE_PAGE_OFF_BUDDY > > + bool> + > > config MEMORY_FAILURE > > depends on MMU > > depends on ARCH_SUPPORTS_MEMORY_FAILURE > > bool "Enable recovery from hardware memory errors" > > select MEMORY_ISOLATION > > select RAS > > + select WANTS_TAKE_PAGE_OFF_BUDDY > > help > > Enables code to recover from some memory failures on systems > > with MCA recovery. This allows a system to continue running > > @@ -891,6 +895,7 @@ config CMA > > depends on MMU > > select MIGRATION > > select MEMORY_ISOLATION > > + select WANTS_TAKE_PAGE_OFF_BUDDY > > help > > This enables the Contiguous Memory Allocator which allows other > > subsystems to allocate big physically-contiguous blocks of memory. > > diff --git a/mm/cma.c b/mm/cma.c > > index 2881bab12b01..15663f95d77b 100644 > > --- a/mm/cma.c > > +++ b/mm/cma.c > > @@ -444,6 +444,34 @@ static void cma_debug_show_areas(struct cma *cma) > > static inline void cma_debug_show_areas(struct cma *cma) { } > > #endif > > > > +/* Called with the cma mutex held. */ > > +static int cma_alloc_pages_fastpath(struct cma *cma, unsigned long start, > > + unsigned long end) > > +{ > > + bool success = false; > > + unsigned long i, j; > > + > > + /* Avoid contention on the zone lock. */ > > + if (start - end != 1 << cma->order_per_bit) > > + return -EINVAL; > > + > > + for (i = start; i < end; i++) { > > + if (!is_free_buddy_page(pfn_to_page(i))) > > + break; > > + success = take_page_off_buddy(pfn_to_page(i), false); > > + if (!success) > > + break; > > + } > > + > > + if (success) > > + return 0; > > + > > + for (j = start; j < i; j++) > > + put_page_back_buddy(pfn_to_page(j), false); > > + > > + return -EBUSY; > > +} > > + > > /** > > * cma_alloc_range() - allocate pages in a specific range > > * @cma: Contiguous memory region for which the allocation is performed. > > @@ -493,7 +521,11 @@ int cma_alloc_range(struct cma *cma, unsigned long start, unsigned long count, > > > > for (i = 0; i < tries; i++) { > > mutex_lock(&cma_mutex); > > - err = alloc_contig_range(start, start + count, MIGRATE_CMA, gfp); > > + err = cma_alloc_pages_fastpath(cma, start, start + count); > > + if (err) { > > + err = alloc_contig_range(start, start + count, > > + MIGRATE_CMA, gfp); > > + } > > mutex_unlock(&cma_mutex); > > > > if (err != -EBUSY) > > @@ -529,7 +561,6 @@ int cma_alloc_range(struct cma *cma, unsigned long start, unsigned long count, > > return err; > > } > > > > - > > /** > > * cma_alloc() - allocate pages from contiguous area > > * @cma: Contiguous memory region for which the allocation is performed. > > @@ -589,8 +620,11 @@ struct page *cma_alloc(struct cma *cma, unsigned long count, > > > > pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit); > > mutex_lock(&cma_mutex); > > - ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA, > > - GFP_KERNEL | (no_warn ? __GFP_NOWARN : 0)); > > + ret = cma_alloc_pages_fastpath(cma, pfn, pfn + count); > > + if (ret) { > > + ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA, > > + GFP_KERNEL | (no_warn ? __GFP_NOWARN : 0)); > > + } > > mutex_unlock(&cma_mutex); > > if (ret == 0) { > > page = pfn_to_page(pfn); > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > > index 4f9b61f4a668..b87b533a9871 100644 > > --- a/mm/memory-failure.c > > +++ b/mm/memory-failure.c > > @@ -157,7 +157,7 @@ static int __page_handle_poison(struct page *page) > > zone_pcp_disable(page_zone(page)); > > ret = dissolve_free_huge_page(page); > > if (!ret) > > - ret = take_page_off_buddy(page); > > + ret = take_page_off_buddy(page, true); > > zone_pcp_enable(page_zone(page)); > > > > return ret; > > @@ -1353,7 +1353,7 @@ static int page_action(struct page_state *ps, struct page *p, > > return action_result(pfn, ps->type, result); > > } > > > > -static inline bool PageHWPoisonTakenOff(struct page *page) > > +bool PageHWPoisonTakenOff(struct page *page) > > { > > return PageHWPoison(page) && page_private(page) == MAGIC_HWPOISON; > > } > > @@ -2247,7 +2247,7 @@ int memory_failure(unsigned long pfn, int flags) > > res = get_hwpoison_page(p, flags); > > if (!res) { > > if (is_free_buddy_page(p)) { > > - if (take_page_off_buddy(p)) { > > + if (take_page_off_buddy(p, true)) { > > page_ref_inc(p); > > res = MF_RECOVERED; > > } else { > > @@ -2578,7 +2578,7 @@ int unpoison_memory(unsigned long pfn) > > ret = folio_test_clear_hwpoison(folio) ? 0 : -EBUSY; > > } else if (ghp < 0) { > > if (ghp == -EHWPOISON) { > > - ret = put_page_back_buddy(p) ? 0 : -EBUSY; > > + ret = put_page_back_buddy(p, true) ? 0 : -EBUSY; > > } else { > > ret = ghp; > > unpoison_pr_info("Unpoison: failed to grab page %#lx\n", > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 0fa34bcfb1af..502ee3eb8583 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -6655,7 +6655,7 @@ bool is_free_buddy_page(struct page *page) > > } > > EXPORT_SYMBOL(is_free_buddy_page); > > > > -#ifdef CONFIG_MEMORY_FAILURE > > +#ifdef CONFIG_WANTS_TAKE_PAGE_OFF_BUDDY > > /* > > * Break down a higher-order page in sub-pages, and keep our target out of > > * buddy allocator. > > @@ -6687,9 +6687,9 @@ static void break_down_buddy_pages(struct zone *zone, struct page *page, > > } > > > > /* > > - * Take a page that will be marked as poisoned off the buddy allocator. > > + * Take a page off the buddy allocator, and optionally mark it as poisoned. > > */ > > -bool take_page_off_buddy(struct page *page) > > +bool take_page_off_buddy(struct page *page, bool poison) > > { > > struct zone *zone = page_zone(page); > > unsigned long pfn = page_to_pfn(page); > > @@ -6710,7 +6710,8 @@ bool take_page_off_buddy(struct page *page) > > del_page_from_free_list(page_head, zone, page_order); > > break_down_buddy_pages(zone, page_head, page, 0, > > page_order, migratetype); > > - SetPageHWPoisonTakenOff(page); > > + if (poison) > > + SetPageHWPoisonTakenOff(page); > > if (!is_migrate_isolate(migratetype)) > > __mod_zone_freepage_state(zone, -1, migratetype); > > ret = true; > > @@ -6724,9 +6725,10 @@ bool take_page_off_buddy(struct page *page) > > } > > > > /* > > - * Cancel takeoff done by take_page_off_buddy(). > > + * Cancel takeoff done by take_page_off_buddy(), and optionally unpoison the > > + * page. > > */ > > -bool put_page_back_buddy(struct page *page) > > +bool put_page_back_buddy(struct page *page, bool unpoison) > > { > > struct zone *zone = page_zone(page); > > unsigned long pfn = page_to_pfn(page); > > @@ -6736,17 +6738,18 @@ bool put_page_back_buddy(struct page *page) > > > > spin_lock_irqsave(&zone->lock, flags); > > if (put_page_testzero(page)) { > > - ClearPageHWPoisonTakenOff(page); > > + VM_WARN_ON_ONCE(PageHWPoisonTakenOff(page) && !unpoison); > > + if (unpoison) > > + ClearPageHWPoisonTakenOff(page); > > __free_one_page(page, pfn, zone, 0, migratetype, FPI_NONE); > > - if (TestClearPageHWPoison(page)) { > > + if (!unpoison || (unpoison && TestClearPageHWPoison(page))) > > ret = true; > > - } > > } > > spin_unlock_irqrestore(&zone->lock, flags); > > > > return ret; > > } > > -#endif > > +#endif /* CONFIG_WANTS_TAKE_PAGE_OFF_BUDDY */ > > > > #ifdef CONFIG_ZONE_DMA > > bool has_managed_dma(void)
