Hi, On Tue, Nov 10, 2020 at 03:36:20PM -0800, Minchan Kim wrote: > On Tue, Nov 10, 2020 at 06:21:55PM +0200, Mike Rapoport wrote: > > On Tue, Nov 10, 2020 at 12:21:11PM +0100, Arnd Bergmann wrote: > > > On Tue, Nov 10, 2020 at 10:58 AM Mike Rapoport <rppt@xxxxxxxxxx> wrote: > > > > > > > > > > > > asm/sparsemem.h is not available on some architectures. > > > > > > It's better to use linux/mmzone.h instead. > > > > > > Ah, I missed that, too. > > > > > > > > Hm, linux/mmzone.h only includes asm/sparsemem.h when CONFIG_SPARSEMEM > > > > > is enabled. However, on ARM at least I can have configurations without > > > > > CONFIG_SPARSEMEM and physical address extension on (e.g. > > > > > multi_v7_defconfig + CONFIG_LPAE + CONFIG_ZSMALLOC). > > > > > > > > > > While sparsemem seems to be a good idea with LPAE it really seems not > > > > > required (see also https://lore.kernel.org/patchwork/patch/567589/). > > > > > > > > > > There seem to be also other architectures which define MAX_PHYSMEM_BITS > > > > > only when SPARSEMEM is enabled, e.g. > > > > > arch/riscv/include/asm/sparsemem.h... > > > > > > > > > > Not sure how to get out of this.. Maybe make ZSMALLOC dependent on > > > > > SPARSEMEM? It feels a bit silly restricting ZSMALLOC selection only due > > > > > to a compile time define... > > > > > > > > I think we can define MAX_POSSIBLE_PHYSMEM_BITS in one of > > > > arch/arm/inclide/asm/pgtable-{2,3}level-*.h headers to values supported > > > > by !LPAE and LPAE. > > > > > > Good idea. I wonder what other architectures need the same though. > > > Here are some I found: > > > > > > $ git grep -l PHYS_ADDR_T_64BIT arch | grep Kconfig > > > arch/arc/Kconfig > > > arch/arm/mm/Kconfig > > > arch/mips/Kconfig > > > arch/powerpc/platforms/Kconfig.cputype > > > arch/x86/Kconfig > > > > > > arch/arc has a CONFIG_ARC_HAS_PAE40 option > > > arch/riscv has 34-bit addressing in rv32 mode > > > arch/mips has up to 40 bits with mips32r3 XPA, but I don't know what > > > supports that > > > > > > arch/powerpc has this: > > > config PHYS_64BIT > > > bool 'Large physical address support' if E500 || PPC_86xx > > > depends on (44x || E500 || PPC_86xx) && !PPC_83xx && !PPC_82xx > > > > > > Apparently all three (4xx, e500v2, mpc86xx/e600) do 36-bit physical > > > addressing, but each one has a different page table format. > > > > > > Microblaze has physical address extensions, but neither those nor > > > 64-bit mode have so far made it into the kernel. > > > > > > To be on the safe side, we could provoke a compile-time error > > > when CONFIG_PHYS_ADDR_T_64BIT is set on a 32-bit > > > architecture, but MAX_POSSIBLE_PHYSMEM_BITS is not set. > > > > Maybe compile time warning and a runtime error in zs_init() if 32 bit > > machine has memory above 4G? > > I guess max_pfn will represent maximum pfn configued in the system > and will not be changed in the runtime. If it's true, how about this? > (didn't test at all but just for RFC) Largely, max_pfn is the maximal pfn at boot time but I don't think it can be used on systems with memory hotplug. Unless I'm missing something, with memory hotplug we must have compile-time maximum. > From 2f51a743a08d10c787a36912515a91826693e308 Mon Sep 17 00:00:00 2001 > From: Minchan Kim <minchan@xxxxxxxxxx> > Date: Tue, 10 Nov 2020 15:17:12 -0800 > Subject: [PATCH] zsmalloc: do not support if system has too big memory > > zsmalloc encode object location into unsigned long so if the system > has too big memory to encode the object location into BITS_PER_LONG, > it should return the error. Otherwise, system will be crash. > > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> > --- > mm/zsmalloc.c | 82 ++++++++++++++++++++++++++++----------------------- > 1 file changed, 45 insertions(+), 37 deletions(-) > > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index 662ee420706f..13552f412ca1 100644 > --- a/mm/zsmalloc.c > +++ b/mm/zsmalloc.c > @@ -87,19 +87,8 @@ > * This is made more complicated by various memory models and PAE. > */ > > -#ifndef MAX_POSSIBLE_PHYSMEM_BITS > -#ifdef MAX_PHYSMEM_BITS > -#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS > -#else > -/* > - * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just > - * be PAGE_SHIFT > - */ > -#define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG > -#endif > -#endif > - > -#define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) > +static unsigned int pfn_bits; > +static unsigned int obj_index_bits; > > /* > * Memory for allocating for handle keeps object position by > @@ -119,18 +108,20 @@ > */ > #define OBJ_ALLOCATED_TAG 1 > #define OBJ_TAG_BITS 1 > -#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS) > -#define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1) > +static unsigned int obj_index_mask; > > #define FULLNESS_BITS 2 > #define CLASS_BITS 8 > #define ISOLATED_BITS 3 > #define MAGIC_VAL_BITS 8 > > -#define MAX(a, b) ((a) >= (b) ? (a) : (b)) > -/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */ > -#define ZS_MIN_ALLOC_SIZE \ > - MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS)) > +/* zs_min_alloc_size must be multiple of ZS_ALIGN */ > +int zs_min_alloc_size(void) > +{ > + return max_t(unsigned long, 32, ZS_MAX_PAGES_PER_ZSPAGE << > + PAGE_SHIFT >> obj_index_bits); > +} > + > /* each chunk includes extra space to keep handle */ > #define ZS_MAX_ALLOC_SIZE PAGE_SIZE > > @@ -144,12 +135,11 @@ > * determined). NOTE: all those class sizes must be set as multiple of > * ZS_ALIGN to make sure link_free itself never has to span 2 pages. > * > - * ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN > + * zs_min_alloc_size and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN > * (reason above) > */ > #define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> CLASS_BITS) > -#define ZS_SIZE_CLASSES (DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \ > - ZS_SIZE_CLASS_DELTA) + 1) > +static unsigned int zs_size_classes; > > enum fullness_group { > ZS_EMPTY, > @@ -253,7 +243,7 @@ struct link_free { > struct zs_pool { > const char *name; > > - struct size_class *size_class[ZS_SIZE_CLASSES]; > + struct size_class **size_class; > struct kmem_cache *handle_cachep; > struct kmem_cache *zspage_cachep; > > @@ -541,11 +531,11 @@ static int get_size_class_index(int size) > { > int idx = 0; > > - if (likely(size > ZS_MIN_ALLOC_SIZE)) > - idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE, > + if (likely(size > zs_min_alloc_size())) > + idx = DIV_ROUND_UP(size - zs_min_alloc_size(), > ZS_SIZE_CLASS_DELTA); > > - return min_t(int, ZS_SIZE_CLASSES - 1, idx); > + return min_t(int, zs_size_classes - 1, idx); > } > > /* type can be of enum type zs_stat_type or fullness_group */ > @@ -605,7 +595,7 @@ static int zs_stats_size_show(struct seq_file *s, void *v) > "obj_allocated", "obj_used", "pages_used", > "pages_per_zspage", "freeable"); > > - for (i = 0; i < ZS_SIZE_CLASSES; i++) { > + for (i = 0; i < zs_size_classes; i++) { > class = pool->size_class[i]; > > if (class->index != i) > @@ -845,8 +835,8 @@ static void obj_to_location(unsigned long obj, struct page **page, > unsigned int *obj_idx) > { > obj >>= OBJ_TAG_BITS; > - *page = pfn_to_page(obj >> OBJ_INDEX_BITS); > - *obj_idx = (obj & OBJ_INDEX_MASK); > + *page = pfn_to_page(obj >> obj_index_bits); > + *obj_idx = (obj & obj_index_mask); > } > > /** > @@ -858,8 +848,8 @@ static unsigned long location_to_obj(struct page *page, unsigned int obj_idx) > { > unsigned long obj; > > - obj = page_to_pfn(page) << OBJ_INDEX_BITS; > - obj |= obj_idx & OBJ_INDEX_MASK; > + obj = page_to_pfn(page) << obj_index_bits; > + obj |= obj_idx & obj_index_mask; > obj <<= OBJ_TAG_BITS; > > return obj; > @@ -2202,7 +2192,7 @@ static void async_free_zspage(struct work_struct *work) > struct zs_pool *pool = container_of(work, struct zs_pool, > free_work); > > - for (i = 0; i < ZS_SIZE_CLASSES; i++) { > + for (i = 0; i < zs_size_classes; i++) { > class = pool->size_class[i]; > if (class->index != i) > continue; > @@ -2320,7 +2310,7 @@ unsigned long zs_compact(struct zs_pool *pool) > int i; > struct size_class *class; > > - for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) { > + for (i = zs_size_classes - 1; i >= 0; i--) { > class = pool->size_class[i]; > if (!class) > continue; > @@ -2366,7 +2356,7 @@ static unsigned long zs_shrinker_count(struct shrinker *shrinker, > struct zs_pool *pool = container_of(shrinker, struct zs_pool, > shrinker); > > - for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) { > + for (i = zs_size_classes - 1; i >= 0; i--) { > class = pool->size_class[i]; > if (!class) > continue; > @@ -2427,18 +2417,20 @@ struct zs_pool *zs_create_pool(const char *name) > if (create_cache(pool)) > goto err; > > + pool->size_class = kmalloc(sizeof(void *) * zs_size_classes, GFP_KERNEL); > + > /* > * Iterate reversely, because, size of size_class that we want to use > * for merging should be larger or equal to current size. > */ > - for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) { > + for (i = zs_size_classes - 1; i >= 0; i--) { > int size; > int pages_per_zspage; > int objs_per_zspage; > struct size_class *class; > int fullness = 0; > > - size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA; > + size = zs_min_alloc_size() + i * ZS_SIZE_CLASS_DELTA; > if (size > ZS_MAX_ALLOC_SIZE) > size = ZS_MAX_ALLOC_SIZE; > pages_per_zspage = get_pages_per_zspage(size); > @@ -2528,7 +2520,7 @@ void zs_destroy_pool(struct zs_pool *pool) > zs_unregister_migration(pool); > zs_pool_stat_destroy(pool); > > - for (i = 0; i < ZS_SIZE_CLASSES; i++) { > + for (i = 0; i < zs_size_classes; i++) { > int fg; > struct size_class *class = pool->size_class[i]; > > @@ -2547,6 +2539,7 @@ void zs_destroy_pool(struct zs_pool *pool) > kfree(class); > } > > + kfree(pool->size_class); > destroy_cache(pool); > kfree(pool->name); > kfree(pool); > @@ -2557,6 +2550,21 @@ static int __init zs_init(void) > { > int ret; > > + /* > + * If BITS_PER_LONG is not big enough to encode metadata(e.g., object > + * location and some tags), it could't work at this moment. > + */ > + pfn_bits = ilog2(max_pfn) + 1; > + if (BITS_PER_LONG - OBJ_TAG_BITS - pfn_bits < 0) { > + pr_warn("max_pfn %lu is too large for zsmalloc\n", > + max_pfn); > + return -EFBIG; > + } > + > + obj_index_bits = BITS_PER_LONG - OBJ_TAG_BITS - pfn_bits; > + obj_index_mask = (1 << obj_index_bits) - 1; > + zs_size_classes = (DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - zs_min_alloc_size(), ZS_SIZE_CLASS_DELTA) + 1); > + > ret = zsmalloc_mount(); > if (ret) > goto out; > -- > 2.29.2.299.gdc1121823c-goog > -- Sincerely yours, Mike.
