09.03.2021 09:23, Minchan Kim пишет: > Since CMA is getting used more widely, it's more important to > keep monitoring CMA statistics for system health since it's > directly related to user experience. > > This patch introduces sysfs statistics for CMA, in order to provide > some basic monitoring of the CMA allocator. > > * the number of CMA page successful allocations > * the number of CMA page allocation failures > > These two values allow the user to calcuate the allocation > failure rate for each CMA area. > > e.g.) > /sys/kernel/mm/cma/WIFI/alloc_pages_[success|fail] > /sys/kernel/mm/cma/SENSOR/alloc_pages_[success|fail] > /sys/kernel/mm/cma/BLUETOOTH/alloc_pages_[success|fail] > > The cma_stat was intentionally allocated by dynamic allocation > to harmonize with kobject lifetime management. > https://lore.kernel.org/linux-mm/YCOAmXqt6dZkCQYs@xxxxxxxxx/ > > Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx> > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> > --- > From v3 - https://lore.kernel.org/linux-mm/20210303205053.2906924-1-minchan@xxxxxxxxxx/ > * fix ZERO_OR_NULL_PTR - kernel test robot > * remove prefix cma - david@ > * resolve conflict with vmstat cma in mmotm - akpm@ > * rename stat name with success|fail > > From v2 - https://lore.kernel.org/linux-mm/20210208180142.2765456-1-minchan@xxxxxxxxxx/ > * sysfs doc and description modification - jhubbard > > From v1 - https://lore.kernel.org/linux-mm/20210203155001.4121868-1-minchan@xxxxxxxxxx/ > * fix sysfs build and refactoring - willy > * rename and drop some attributes - jhubbard > > Documentation/ABI/testing/sysfs-kernel-mm-cma | 25 ++++ > mm/Kconfig | 7 ++ > mm/Makefile | 1 + > mm/cma.c | 7 +- > mm/cma.h | 20 ++++ > mm/cma_sysfs.c | 110 ++++++++++++++++++ > 6 files changed, 168 insertions(+), 2 deletions(-) > create mode 100644 Documentation/ABI/testing/sysfs-kernel-mm-cma > create mode 100644 mm/cma_sysfs.c > > diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-cma b/Documentation/ABI/testing/sysfs-kernel-mm-cma > new file mode 100644 > index 000000000000..02b2bb60c296 > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-kernel-mm-cma > @@ -0,0 +1,25 @@ > +What: /sys/kernel/mm/cma/ > +Date: Feb 2021 > +Contact: Minchan Kim <minchan@xxxxxxxxxx> > +Description: > + /sys/kernel/mm/cma/ contains a subdirectory for each CMA > + heap name (also sometimes called CMA areas). > + > + Each CMA heap subdirectory (that is, each > + /sys/kernel/mm/cma/<cma-heap-name> directory) contains the > + following items: > + > + alloc_pages_success > + alloc_pages_fail > + > +What: /sys/kernel/mm/cma/<cma-heap-name>/alloc_pages_success > +Date: Feb 2021 > +Contact: Minchan Kim <minchan@xxxxxxxxxx> > +Description: > + the number of pages CMA API succeeded to allocate > + > +What: /sys/kernel/mm/cma/<cma-heap-name>/alloc_pages_fail > +Date: Feb 2021 > +Contact: Minchan Kim <minchan@xxxxxxxxxx> > +Description: > + the number of pages CMA API failed to allocate > diff --git a/mm/Kconfig b/mm/Kconfig > index 24c045b24b95..febb7e8e24de 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -513,6 +513,13 @@ config CMA_DEBUGFS > help > Turns on the DebugFS interface for CMA. > > +config CMA_SYSFS > + bool "CMA information through sysfs interface" > + depends on CMA && SYSFS > + help > + This option exposes some sysfs attributes to get information > + from CMA. > + > config CMA_AREAS > int "Maximum count of the CMA areas" > depends on CMA > diff --git a/mm/Makefile b/mm/Makefile > index 72227b24a616..56968b23ed7a 100644 > --- a/mm/Makefile > +++ b/mm/Makefile > @@ -109,6 +109,7 @@ obj-$(CONFIG_CMA) += cma.o > obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o > obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o > obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o > +obj-$(CONFIG_CMA_SYSFS) += cma_sysfs.o > obj-$(CONFIG_USERFAULTFD) += userfaultfd.o > obj-$(CONFIG_IDLE_PAGE_TRACKING) += page_idle.o > obj-$(CONFIG_DEBUG_PAGE_REF) += debug_page_ref.o > diff --git a/mm/cma.c b/mm/cma.c > index 908f04775686..ac050359faae 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -507,10 +507,13 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, > > pr_debug("%s(): returned %p\n", __func__, page); > out: > - if (page) > + if (page) { > count_vm_event(CMA_ALLOC_SUCCESS); > - else > + cma_sysfs_alloc_pages_count(cma, count); > + } else { > count_vm_event(CMA_ALLOC_FAIL); > + cma_sysfs_fail_pages_count(cma, count); > + } > > return page; > } > diff --git a/mm/cma.h b/mm/cma.h > index 42ae082cb067..95d1aa2d808a 100644 > --- a/mm/cma.h > +++ b/mm/cma.h > @@ -3,6 +3,16 @@ > #define __MM_CMA_H__ > > #include <linux/debugfs.h> > +#include <linux/kobject.h> > + > +struct cma_stat { > + spinlock_t lock; > + /* the number of CMA page successful allocations */ > + unsigned long nr_pages_succeeded; > + /* the number of CMA page allocation failures */ > + unsigned long nr_pages_failed; > + struct kobject kobj; > +}; > > struct cma { > unsigned long base_pfn; > @@ -16,6 +26,9 @@ struct cma { > struct debugfs_u32_array dfs_bitmap; > #endif > char name[CMA_MAX_NAME]; > +#ifdef CONFIG_CMA_SYSFS > + struct cma_stat *stat; > +#endif > }; > > extern struct cma cma_areas[MAX_CMA_AREAS]; > @@ -26,4 +39,11 @@ static inline unsigned long cma_bitmap_maxno(struct cma *cma) > return cma->count >> cma->order_per_bit; > } > > +#ifdef CONFIG_CMA_SYSFS > +void cma_sysfs_alloc_pages_count(struct cma *cma, size_t count); > +void cma_sysfs_fail_pages_count(struct cma *cma, size_t count); > +#else > +static inline void cma_sysfs_alloc_pages_count(struct cma *cma, size_t count) {}; > +static inline void cma_sysfs_fail_pages_count(struct cma *cma, size_t count) {}; > +#endif > #endif > diff --git a/mm/cma_sysfs.c b/mm/cma_sysfs.c > new file mode 100644 > index 000000000000..3134b2b3a96d > --- /dev/null > +++ b/mm/cma_sysfs.c > @@ -0,0 +1,110 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * CMA SysFS Interface > + * > + * Copyright (c) 2021 Minchan Kim <minchan@xxxxxxxxxx> > + */ > + > +#include <linux/cma.h> > +#include <linux/kernel.h> > +#include <linux/slab.h> > + > +#include "cma.h" > + > +static struct cma_stat *cma_stats; > + > +void cma_sysfs_alloc_pages_count(struct cma *cma, size_t count) > +{ > + spin_lock(&cma->stat->lock); > + cma->stat->nr_pages_succeeded += count; > + spin_unlock(&cma->stat->lock); > +} > + > +void cma_sysfs_fail_pages_count(struct cma *cma, size_t count) > +{ > + spin_lock(&cma->stat->lock); > + cma->stat->nr_pages_failed += count; > + spin_unlock(&cma->stat->lock); > +} > + > +#define CMA_ATTR_RO(_name) \ > + static struct kobj_attribute _name##_attr = __ATTR_RO(_name) > + > +static struct kobject *cma_kobj; > + > +static ssize_t alloc_pages_success_show(struct kobject *kobj, > + struct kobj_attribute *attr, char *buf) > +{ > + struct cma_stat *stat = container_of(kobj, struct cma_stat, kobj); > + > + return sysfs_emit(buf, "%lu\n", stat->nr_pages_succeeded); > +} > +CMA_ATTR_RO(alloc_pages_success); > + > +static ssize_t alloc_pages_fail_show(struct kobject *kobj, > + struct kobj_attribute *attr, char *buf) > +{ > + struct cma_stat *stat = container_of(kobj, struct cma_stat, kobj); > + > + return sysfs_emit(buf, "%lu\n", stat->nr_pages_failed); > +} > +CMA_ATTR_RO(alloc_pages_fail); > + > +static void cma_kobj_release(struct kobject *kobj) > +{ > + struct cma_stat *stat = container_of(kobj, struct cma_stat, kobj); > + > + kfree(stat); > +} > + > +static struct attribute *cma_attrs[] = { > + &alloc_pages_success_attr.attr, > + &alloc_pages_fail_attr.attr, > + NULL, > +}; > +ATTRIBUTE_GROUPS(cma); > + > +static struct kobj_type cma_ktype = { > + .release = cma_kobj_release, > + .sysfs_ops = &kobj_sysfs_ops, > + .default_groups = cma_groups > +}; > + > +static int __init cma_sysfs_init(void) > +{ > + int i = 0; > + struct cma *cma; > + > + cma_kobj = kobject_create_and_add("cma", mm_kobj); > + if (!cma_kobj) > + return -ENOMEM; > + > + cma_stats = kmalloc_array(cma_area_count, sizeof(struct cma_stat), > + GFP_KERNEL|__GFP_ZERO); Use kcalloc(). Code identation is wrong, please use checkpatch. > + if (ZERO_OR_NULL_PTR(cma_stats)) > + goto out; > + > + do { > + cma = &cma_areas[i]; > + cma->stat = &cma_stats[i]; > + spin_lock_init(&cma->stat->lock); > + if (kobject_init_and_add(&cma->stat->kobj, &cma_ktype, > + cma_kobj, "%s", cma->name)) { > + kobject_put(&cma->stat->kobj); > + goto out; > + } > + } while (++i < cma_area_count); > + > + return 0; > +out: > + while (--i >= 0) { > + cma = &cma_areas[i]; > + kobject_put(&cma->stat->kobj); > + } > + > + kfree(cma_stats); > + kobject_put(cma_kobj); > + > + return -ENOMEM; > +} > +subsys_initcall(cma_sysfs_init); > Hi, There is a NULL derence on ARM32 NVIDIA Tegra SoCs with CONFIG_CMA_SYSFS=y using today's next-20210319, please take a look. [ 1.185423] 8<--- cut here --- [ 1.186081] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 1.186705] pgd = (ptrval) [ 1.188130] [00000000] *pgd=00000000 [ 1.190554] Internal error: Oops: 5 [#1] PREEMPT SMP THUMB2 [ 1.191545] Modules linked in: [ 1.192629] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W 5.12.0-rc3-next-20210319-00174-g89b3b421dd2b #7142 [ 1.193540] Hardware name: NVIDIA Tegra SoC (Flattened Device Tree) [ 1.194613] PC is at _raw_spin_lock+0x1a/0x48 [ 1.200352] LR is at cma_sysfs_alloc_pages_count+0x13/0x24 [ 1.200821] pc : [<c0a2d832>] lr : [<c027762f>] psr: 00000033 [ 1.201269] sp : c1547e48 ip : f0000080 fp : 0000c800 [ 1.201580] r10: c13bd178 r9 : 00000040 r8 : 00000040 [ 1.201972] r7 : 00000000 r6 : c13bd168 r5 : 00000040 r4 : c13bd168 [ 1.202418] r3 : c1546000 r2 : 00000001 r1 : 00000040 r0 : 00000000 [ 1.203014] Flags: nzcv IRQs on FIQs on Mode SVC_32 ISA Thumb Segment none [ 1.203488] Control: 50c5387d Table: 0000406a DAC: 00000051 [ 1.203988] Register r0 information: NULL pointer [ 1.204868] Register r1 information: non-paged memory [ 1.205233] Register r2 information: non-paged memory [ 1.205563] Register r3 information: non-slab/vmalloc memory [ 1.206213] Register r4 information: non-slab/vmalloc memory [ 1.206578] Register r5 information: non-paged memory [ 1.206929] Register r6 information: non-slab/vmalloc memory [ 1.207278] Register r7 information: NULL pointer [ 1.207594] Register r8 information: non-paged memory [ 1.207968] Register r9 information: non-paged memory [ 1.208291] Register r10 information: non-slab/vmalloc memory [ 1.208648] Register r11 information: non-paged memory [ 1.209002] Register r12 information: non-paged memory [ 1.209407] Process swapper/0 (pid: 1, stack limit = 0x(ptrval)) [ 1.209956] Stack: (0xc1547e48 to 0xc1548000) [ 1.211102] 7e40: c1199e24 00033800 efe35000 c027706f 0000003f 00000000 [ 1.211999] 7e60: 00000040 0000003f 00000000 00000040 00000cc0 00000000 00000006 00000000 [ 1.212855] 7e80: c1547ed8 00040000 c1141780 00000001 00000000 c1547ed8 00000647 00000040 [ 1.213768] 7ea0: c138c000 c01112ab c0fed0d8 c1141780 c1546000 00000001 c1140d24 00000000 [ 1.214648] 7ec0: c1140d44 c1104af9 c1104a7f 00000001 00000000 00000cc0 00000000 e29968ad [ 1.215578] 7ee0: c161a077 c1546000 c136d940 c1104a7f ffffe000 c0101d69 c161a077 c161a098 [ 1.216564] 7f00: c1058490 c0138345 c10566cc c0ef58b8 c11003d1 c1546000 00000000 00000002 [ 1.217357] 7f20: 00000002 c0f10280 c0efe3e4 c0efe398 c11003d1 c161a074 c161a077 e29968ad [ 1.218212] 7f40: c1140d40 e29968ad c161a000 c118d304 00000003 c11003d1 c161a000 c1140d24 [ 1.219164] 7f60: 0000017e c1101141 00000002 00000002 00000000 c11003d1 c0a27fc5 c10566cc [ 1.220015] 7f80: c1547f98 00000000 c0a27fc5 00000000 00000000 00000000 00000000 00000000 [ 1.220863] 7fa0: 00000000 c0a27fd1 00000000 c0100155 00000000 00000000 00000000 00000000 [ 1.221713] 7fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 [ 1.222584] 7fe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000 [ 1.225038] [<c0a2d832>] (_raw_spin_lock) from [<c027762f>] (cma_sysfs_alloc_pages_count+0x13/0x24) [ 1.226190] [<c027762f>] (cma_sysfs_alloc_pages_count) from [<c027706f>] (cma_alloc+0x153/0x274) [ 1.226720] [<c027706f>] (cma_alloc) from [<c01112ab>] (__alloc_from_contiguous+0x37/0x8c) [ 1.227272] [<c01112ab>] (__alloc_from_contiguous) from [<c1104af9>] (atomic_pool_init+0x7b/0x126) [ 1.233596] [<c1104af9>] (atomic_pool_init) from [<c0101d69>] (do_one_initcall+0x45/0x1e4) [ 1.234188] [<c0101d69>] (do_one_initcall) from [<c1101141>] (kernel_init_freeable+0x157/0x1a6) [ 1.234741] [<c1101141>] (kernel_init_freeable) from [<c0a27fd1>] (kernel_init+0xd/0xe0) [ 1.235289] [<c0a27fd1>] (kernel_init) from [<c0100155>] (ret_from_fork+0x11/0x1c)
