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[PATCH OLK-6.6] fs/dcache.c: avoid panic while lockref of dentry overflow
by Zizhi Wo 09 Jan '24

09 Jan '24

From: yangerkun <yangerkun(a)huawei.com> hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8JDP6 --------------------------- We use lockref for dentry reference without notice that so many negative dentry under one dir can lead to overflow of lockref. This can lead to system crash if we do this under root dir. Since there is not a perfect solution, we just limit max number of dentry count up to INT_MAX / 2. Also, it will cost a lot of time from INT_MAX / 2 to INT_MAX, so we no need to do this under protection of dentry lock. Also, we limit the FILES_MAX to INT_MAX / 2, since a lot open for same file can lead to overflow too. Changelog: v1->v2: add a function to do check / add a Macro to mean INT_MAX / 2 Signed-off-by: yangerkun <yangerkun(a)huawei.com> Signed-off-by: Zizhi Wo <wozizhi(a)huawei.com> --- fs/dcache.c | 32 ++++++++++++++++++++++++++++---- fs/filescontrol.c | 2 +- include/linux/fs.h | 3 +++ 3 files changed, 32 insertions(+), 5 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 25ac74d30bff..7cdd8bbedd1c 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1834,6 +1834,18 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) return dentry; } +static inline bool d_forbid_overflow(struct dentry *dentry) +{ + if (unlikely(d_count(dentry) >= D_COUNT_MAX)) { + shrink_dcache_parent(dentry); + + if (d_count(dentry) >= D_COUNT_MAX) + return false; + } + + return true; +} + /** * d_alloc - allocate a dcache entry * @parent: parent of entry to allocate @@ -1845,9 +1857,15 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) */ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) { - struct dentry *dentry = __d_alloc(parent->d_sb, name); + struct dentry *dentry = NULL; + + if (unlikely(!d_forbid_overflow(parent))) + goto out; + + dentry = __d_alloc(parent->d_sb, name); if (!dentry) - return NULL; + goto out; + spin_lock(&parent->d_lock); /* * don't need child lock because it is not subject @@ -1857,7 +1875,7 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) dentry->d_parent = parent; list_add(&dentry->d_child, &parent->d_subdirs); spin_unlock(&parent->d_lock); - +out: return dentry; } EXPORT_SYMBOL(d_alloc); @@ -1870,11 +1888,17 @@ EXPORT_SYMBOL(d_alloc_anon); struct dentry *d_alloc_cursor(struct dentry * parent) { - struct dentry *dentry = d_alloc_anon(parent->d_sb); + struct dentry *dentry = NULL; + + if (unlikely(!d_forbid_overflow(parent))) + goto out; + + dentry = d_alloc_anon(parent->d_sb); if (dentry) { dentry->d_flags |= DCACHE_DENTRY_CURSOR; dentry->d_parent = dget(parent); } +out: return dentry; } diff --git a/fs/filescontrol.c b/fs/filescontrol.c index 610f13a36962..0947566b9119 100644 --- a/fs/filescontrol.c +++ b/fs/filescontrol.c @@ -27,7 +27,7 @@ #include <linux/sched/signal.h> #include <linux/module.h> -#define FILES_MAX ULONG_MAX +#define FILES_MAX D_COUNT_MAX #define FILES_MAX_STR "max" static bool no_acct; diff --git a/include/linux/fs.h b/include/linux/fs.h index fb5accebdcdf..67c2ac09e700 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -47,6 +47,9 @@ #include <asm/byteorder.h> #include <uapi/linux/fs.h> +#define D_COUNT_MAX (INT_MAX / 2) + + struct backing_dev_info; struct bdi_writeback; struct bio; -- 2.39.2

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[PATCH OLK-6.6 0/1] arm64: Add non nmi ipi backtrace support
by Liao Chen 09 Jan '24

09 Jan '24

Dependencies: CONFIG_DETECT_HUNG_TASK=y CONFIG_WATCHDOG=y Li Zhengyu (1): arm64: Add non nmi ipi backtrace support arch/arm64/Kconfig | 8 +++++ arch/arm64/configs/openeuler_defconfig | 1 + arch/arm64/kernel/ipi_nmi.c | 41 ++++++++++++++++++++++---- 3 files changed, 45 insertions(+), 5 deletions(-) -- 2.34.1

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[PATCH OLK-6.6 0/1] arm64: Add non nmi ipi backtrace support
by Liao Chen 09 Jan '24

09 Jan '24

Dependencies: CONFIG_DETECT_HUNG_TASK=y CONFIG_WATCHDOG=y Li Zhengyu (1): arm64: Add non nmi ipi backtrace support arch/arm64/Kconfig | 8 +++++ arch/arm64/configs/openeuler_defconfig | 1 + arch/arm64/kernel/ipi_nmi.c | 41 ++++++++++++++++++++++---- 3 files changed, 45 insertions(+), 5 deletions(-) -- 2.34.1

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[PATCH OLK-6.6 00/10] Backport etmem feature to OLK 6.6
by Yuchen Tang 09 Jan '24

09 Jan '24

v2 -> v3 - fix code style and commit messages v1 -> v2 - make independent patches to export symbols we need - make independent patches for etmem scan and swap config - fix indentation and code style problems Yuchen Tang (10): etmem: add ETMEM feature CONFIG to mm/Kconfig etmem: add ETMEM scan feature CONFIG to mm/Kconfig mm: Export symbol __pud_trans_huge_lock mm: Export symbol walk_page_range etmem: add etmem scan feature mm: Export symbol reclaim_pages etmem: add etmem swap feature etmem: add original kernel swap enabled options etmem: add swapcache reclaim to etmem etmem: enable etmem configurations arch/arm64/configs/openeuler_defconfig | 3 + arch/x86/configs/openeuler_defconfig | 3 + fs/proc/Makefile | 3 + fs/proc/base.c | 8 + fs/proc/etmem_proc.c | 216 ++++ fs/proc/etmem_scan.c | 1383 ++++++++++++++++++++++++ fs/proc/etmem_scan.h | 149 +++ fs/proc/etmem_swap.c | 283 +++++ fs/proc/internal.h | 4 + include/linux/etmem.h | 75 ++ include/linux/mm.h | 4 + include/linux/mm_types.h | 5 + include/linux/swap.h | 1 + include/uapi/asm-generic/mman-common.h | 4 + mm/Kconfig | 33 + mm/Makefile | 1 + mm/etmem.c | 384 +++++++ mm/huge_memory.c | 1 + mm/internal.h | 1 - mm/madvise.c | 16 + mm/pagewalk.c | 1 + mm/swap_state.c | 4 + mm/vmscan.c | 16 + virt/kvm/kvm_main.c | 8 + 24 files changed, 2605 insertions(+), 1 deletion(-) create mode 100644 fs/proc/etmem_proc.c create mode 100644 fs/proc/etmem_scan.c create mode 100644 fs/proc/etmem_scan.h create mode 100644 fs/proc/etmem_swap.c create mode 100644 include/linux/etmem.h create mode 100644 mm/etmem.c -- 2.33.0

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[PATCH OLK-6.6] openeuler_defconfig: set CONFIG_NODES_SHIFT to 8 for both x86_64/ARM64
by Liu Shixin 09 Jan '24

09 Jan '24

hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8UT5S CVE: NA -------------------------------- There is no extra bit in pageflags for new flag on x86_64. Since 256 nodes is enough for x86_64, reduce CONFIG_NODES_SHIFT to 8 to obtain two unused bits on x86_64. On arm64, 128 node is not enough, so raise CONFIG_NODES_SHIFT to 8. Signed-off-by: Liu Shixin <liushixin2(a)huawei.com> --- arch/arm64/configs/openeuler_defconfig | 2 +- arch/x86/configs/openeuler_defconfig | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/configs/openeuler_defconfig b/arch/arm64/configs/openeuler_defconfig index 0f0d9b3d6367..f6d76aa7fd97 100644 --- a/arch/arm64/configs/openeuler_defconfig +++ b/arch/arm64/configs/openeuler_defconfig @@ -450,7 +450,7 @@ CONFIG_NR_CPUS=4096 CONFIG_HOTPLUG_CPU=y # CONFIG_ARM64_BOOTPARAM_HOTPLUG_CPU0 is not set CONFIG_NUMA=y -CONFIG_NODES_SHIFT=7 +CONFIG_NODES_SHIFT=8 # CONFIG_HZ_100 is not set CONFIG_HZ_250=y # CONFIG_HZ_300 is not set diff --git a/arch/x86/configs/openeuler_defconfig b/arch/x86/configs/openeuler_defconfig index 504de984c7be..6b39cf20f8c2 100644 --- a/arch/x86/configs/openeuler_defconfig +++ b/arch/x86/configs/openeuler_defconfig @@ -449,7 +449,7 @@ CONFIG_NUMA_AWARE_SPINLOCKS=y CONFIG_AMD_NUMA=y CONFIG_X86_64_ACPI_NUMA=y CONFIG_NUMA_EMU=y -CONFIG_NODES_SHIFT=10 +CONFIG_NODES_SHIFT=8 CONFIG_ARCH_SPARSEMEM_ENABLE=y CONFIG_ARCH_SPARSEMEM_DEFAULT=y # CONFIG_ARCH_MEMORY_PROBE is not set -- 2.25.1

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[PATCH OLK-6.6 V1 00/12] infrastructure for scheduler bpf
by Lu Jialin 09 Jan '24

09 Jan '24

From: Guan Jing <guanjing6(a)huawei.com> infrastructure for scheduler bpf Guan Jing (12): sched: programmable: Introduce bpf sched sched: programmable: Add a tag for the task sched: programmable: Add a tag for the task group sched: programmable: Add user interface of task group tag sched: programmable: Add user interface of task tag sched: basic infrastructure for scheduler bpf sched: introduce bpf_sched_enable() libbpf: add support for scheduler bpf programs bpftool: recognize scheduler programs sched: Add helper functions to get cpu statistics sched: programmable: Add hook in select_task_rq_fair() sched: programmable: Add hook in can_migrate_task() arch/arm64/configs/openeuler_defconfig | 1 + arch/x86/configs/openeuler_defconfig | 1 + fs/proc/base.c | 64 ++++++++++++++ include/linux/bpf_sched.h | 50 +++++++++++ include/linux/bpf_types.h | 4 + include/linux/sched.h | 38 ++++++++ include/linux/sched_hook_defs.h | 4 + include/uapi/linux/bpf.h | 9 ++ init/init_task.c | 3 + kernel/bpf/Kconfig | 12 +++ kernel/bpf/btf.c | 1 + kernel/bpf/syscall.c | 27 ++++++ kernel/bpf/trampoline.c | 1 + kernel/bpf/verifier.c | 11 ++- kernel/sched/bpf_sched.c | 102 +++++++++++++++++++++ kernel/sched/build_utility.c | 4 + kernel/sched/core.c | 118 +++++++++++++++++++++++++ kernel/sched/fair.c | 45 ++++++++++ kernel/sched/sched.h | 10 +++ scripts/bpf_doc.py | 4 + tools/include/uapi/linux/bpf.h | 9 ++ tools/lib/bpf/bpf.c | 1 + tools/lib/bpf/libbpf.c | 23 ++++- tools/lib/bpf/libbpf.h | 2 + tools/lib/bpf/libbpf.map | 1 + 25 files changed, 543 insertions(+), 2 deletions(-) create mode 100644 include/linux/bpf_sched.h create mode 100644 include/linux/sched_hook_defs.h create mode 100644 kernel/sched/bpf_sched.c -- 2.34.1

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[PATCH OLK-6.6 V1 00/12] infrastructure for scheduler bpf
by Guan Jing 09 Jan '24

09 Jan '24

infrastructure for scheduler bpf Guan Jing (12): sched: programmable: Introduce bpf sched sched: programmable: Add a tag for the task sched: programmable: Add a tag for the task group sched: programmable: Add user interface of task group tag sched: programmable: Add user interface of task tag sched: basic infrastructure for scheduler bpf sched: introduce bpf_sched_enable() libbpf: add support for scheduler bpf programs bpftool: recognize scheduler programs sched: Add helper functions to get cpu statistics sched: programmable: Add hook in select_task_rq_fair() sched: programmable: Add hook in can_migrate_task() arch/arm64/configs/openeuler_defconfig | 1 + arch/x86/configs/openeuler_defconfig | 1 + fs/proc/base.c | 64 ++++++++++++++ include/linux/bpf_sched.h | 50 +++++++++++ include/linux/bpf_types.h | 4 + include/linux/sched.h | 38 ++++++++ include/linux/sched_hook_defs.h | 4 + include/uapi/linux/bpf.h | 9 ++ init/init_task.c | 3 + kernel/bpf/Kconfig | 12 +++ kernel/bpf/btf.c | 1 + kernel/bpf/syscall.c | 27 ++++++ kernel/bpf/trampoline.c | 1 + kernel/bpf/verifier.c | 11 ++- kernel/sched/bpf_sched.c | 102 +++++++++++++++++++++ kernel/sched/build_utility.c | 4 + kernel/sched/core.c | 118 +++++++++++++++++++++++++ kernel/sched/fair.c | 45 ++++++++++ kernel/sched/sched.h | 10 +++ scripts/bpf_doc.py | 4 + tools/include/uapi/linux/bpf.h | 9 ++ tools/lib/bpf/bpf.c | 1 + tools/lib/bpf/libbpf.c | 23 ++++- tools/lib/bpf/libbpf.h | 2 + tools/lib/bpf/libbpf.map | 1 + 25 files changed, 543 insertions(+), 2 deletions(-) create mode 100644 include/linux/bpf_sched.h create mode 100644 include/linux/sched_hook_defs.h create mode 100644 kernel/sched/bpf_sched.c -- 2.34.1

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[PATCH OLK-6.6 0/1] iommu: set CONFIG_SMMU_BYPASS_DEV=y
by zhangnaichuan 09 Jan '24

09 Jan '24

set CONFIG_SMMU_BYPASS_DEV=y in openeuler_defconfig arch/arm64/configs/openeuler_defconfig | 1 + 1 file changed, 1 insertion(+) -- 2.33.0

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[PATCH V3 OLK-6.6] fs/dirty_pages: dump the number of dirty pages for each inode
by Zizhi Wo 09 Jan '24

09 Jan '24

hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8OHM4?from=project-issue CVE: NA ---------------------------------------- In order to analyse the IO performance when using buffer IO, it's useful to obtain the number of dirty pages for each inode in the filesystem. This feature depends on 'CONFIG_DIRTY_PAGES'. It creates 3 interfaces by using procfs. /proc/dirty/buffer_size for buffer allocation and release, /proc/dirty/page_threshold to filter result and /proc/dirty/dirty_list to get dirty pages. Signed-off-by: Zizhi Wo <wozizhi(a)huawei.com> --- arch/arm64/configs/openeuler_defconfig | 1 + arch/x86/configs/openeuler_defconfig | 1 + fs/Kconfig | 13 + fs/Makefile | 1 + fs/dirty_pages.c | 355 +++++++++++++++++++++++++ 5 files changed, 371 insertions(+) create mode 100644 fs/dirty_pages.c diff --git a/arch/arm64/configs/openeuler_defconfig b/arch/arm64/configs/openeuler_defconfig index 66737e8c8673..677b4cc4668a 100644 --- a/arch/arm64/configs/openeuler_defconfig +++ b/arch/arm64/configs/openeuler_defconfig @@ -6924,6 +6924,7 @@ CONFIG_PROC_PAGE_MONITOR=y CONFIG_PROC_CHILDREN=y CONFIG_KERNFS=y CONFIG_SYSFS=y +CONFIG_DIRTY_PAGES=y CONFIG_TMPFS=y CONFIG_TMPFS_POSIX_ACL=y CONFIG_TMPFS_XATTR=y diff --git a/arch/x86/configs/openeuler_defconfig b/arch/x86/configs/openeuler_defconfig index fcbef6c06587..c16cdb7b2596 100644 --- a/arch/x86/configs/openeuler_defconfig +++ b/arch/x86/configs/openeuler_defconfig @@ -8120,6 +8120,7 @@ CONFIG_PROC_PID_ARCH_STATUS=y CONFIG_PROC_CPU_RESCTRL=y CONFIG_KERNFS=y CONFIG_SYSFS=y +CONFIG_DIRTY_PAGES=y CONFIG_TMPFS=y CONFIG_TMPFS_POSIX_ACL=y CONFIG_TMPFS_XATTR=y diff --git a/fs/Kconfig b/fs/Kconfig index 7c9d45ba9b0f..6dc83223c61b 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -170,6 +170,19 @@ source "fs/proc/Kconfig" source "fs/kernfs/Kconfig" source "fs/sysfs/Kconfig" +config DIRTY_PAGES + bool "Dumps the number of dirty pages of each file" + depends on PROC_FS + default y + help + This config supports the rendering of dirty page data to the user, + which may be useful to analyze the IO performance when using buffer + IO. + + It create 3 interfaces by using procfs. /proc/dirty/buffer_size for + buffer allocation and release; /proc/dirty/page_threshold to filter + result; /proc/dirty/dirty_list to get dirty pages. + config TMPFS bool "Tmpfs virtual memory file system support (former shm fs)" depends on SHMEM diff --git a/fs/Makefile b/fs/Makefile index bb6164200a39..cc4735c23c32 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -44,6 +44,7 @@ obj-$(CONFIG_FS_POSIX_ACL) += posix_acl.o obj-$(CONFIG_NFS_COMMON) += nfs_common/ obj-$(CONFIG_COREDUMP) += coredump.o obj-$(CONFIG_SYSCTL) += drop_caches.o sysctls.o +obj-$(CONFIG_DIRTY_PAGES) += dirty_pages.o obj-$(CONFIG_FHANDLE) += fhandle.o obj-$(CONFIG_CGROUP_FILES) += filescontrol.o diff --git a/fs/dirty_pages.c b/fs/dirty_pages.c new file mode 100644 index 000000000000..d0aea022b68b --- /dev/null +++ b/fs/dirty_pages.c @@ -0,0 +1,355 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/proc_fs.h> +#include <linux/seq_file.h> +#include <linux/uaccess.h> +#include <linux/pagemap.h> +#include <linux/pagevec.h> +#include <linux/fs.h> +#include <linux/mm.h> +#include <linux/slab.h> +#include <linux/sched.h> +#include <linux/proc_fs.h> +#include <linux/kdev_t.h> +#include <linux/vmalloc.h> +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include "internal.h" + +#define DIRTY_ROOT "dirty" /* proc root directory name */ +#define DIRTY_BUFFER_SIZE "buffer_size" /* proc file to control buffer */ +#define DIRTY_PAGES "dirty_list" /* proc file to obtain diry pages */ +#define DIRTY_LIMIT "page_threshold" /* proc file to filter result */ +#define MAX_BUF_NUM 102400 /* max buffer num in number of pages */ +#define TERM_STR "terminated\n" /* tail string for overflowed buffer */ +#define UNKNOW_STR "unknown" /* for unknown file name or fs type */ + +static char *buf_dirty; /* buffer to store number of dirty pages */ +static unsigned long buf_size; /* size of buffer in bytes */ +static unsigned long buf_num; /* size of buffer in number of pages */ +static unsigned long buf_limit; /* filter threshold of dirty pages */ +unsigned long lock_word; /* for exclusive access to buffer */ + +static bool dirty_pages_lock(void) +{ + if (xchg(&lock_word, 1) == 1) + return false; + return true; +} + +static void dirty_pages_unlock(void) +{ + lock_word = 0; +} + +static unsigned long dump_dirtypages_inode(struct inode *inode) +{ + XA_STATE(xas, &inode->i_mapping->i_pages, 0); + unsigned long pages = 0; + void *page; + + if (!mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) + return 0; + + xas_lock_irq(&xas); + xas_for_each_marked(&xas, page, (pgoff_t)-1, PAGECACHE_TAG_DIRTY) { + if (++pages % XA_CHECK_SCHED) + continue; + + xas_pause(&xas); + xas_unlock_irq(&xas); + cond_resched(); + xas_lock_irq(&xas); + } + xas_unlock_irq(&xas); + + return pages; +} + +static char *inode_filename(struct inode *inode) +{ + char *path; + static char buf[PATH_MAX]; + struct dentry *dentry; + + dentry = d_find_alias(inode); + if (!dentry) + return UNKNOW_STR; + + path = dentry_path_raw(dentry, buf, PATH_MAX); + dput(dentry); + + return IS_ERR_OR_NULL(path) ? UNKNOW_STR : path; +} + +static const char *sb_fstype(struct super_block *sb) +{ + if (sb->s_type && sb->s_type->name) + return sb->s_type->name; + else + return UNKNOW_STR; +} + +static inline bool is_sb_writable(struct super_block *sb) +{ + if (sb_rdonly(sb)) + return false; + + if (sb->s_writers.frozen == SB_FREEZE_COMPLETE) + return false; + + return true; +} + +/* + * dump_dirtypages_sb - dump the dirty pages of each inode in the sb + * @sb the super block + * @m the seq_file witch is initialized in proc_dpages_open + * + * For each inode in the sb, call dump_dirtypages_pages to get the number + * of dirty pages. And use seq_printf to store the result in the buffer + * if it's not less than the threshold. The inode in unusual state will + * be skipped. + */ +static void dump_dirtypages_sb(struct super_block *sb, struct seq_file *m) +{ + struct inode *inode, *toput_inode = NULL; + unsigned long limit; + + if (!is_sb_writable(sb) || !sb->s_bdev) + return; + + limit = READ_ONCE(buf_limit); + spin_lock(&sb->s_inode_list_lock); + list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { + unsigned long dirty_pages; + + spin_lock(&inode->i_lock); + if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) { + spin_unlock(&inode->i_lock); + continue; + } + + __iget(inode); + spin_unlock(&inode->i_lock); + spin_unlock(&sb->s_inode_list_lock); + + dirty_pages = dump_dirtypages_inode(inode); + if (!dirty_pages || dirty_pages < limit) + goto skip; + + seq_printf(m, "FSType: %s, Dev ID: %u(%u:%u) ino %lu, dirty pages %lu, path %s\n", + sb_fstype(sb), sb->s_dev, MAJOR(sb->s_dev), + MINOR(sb->s_dev), inode->i_ino, dirty_pages, + inode_filename(inode)); + + if (seq_has_overflowed(m)) { + /* keep size > count to avoid overflow in seq_read_iter() */ + m->size += strlen(TERM_STR) + 1; + seq_puts(m, TERM_STR); + iput(inode); + iput(toput_inode); + return; + } +skip: + iput(toput_inode); + toput_inode = inode; + cond_resched(); + spin_lock(&sb->s_inode_list_lock); + } + spin_unlock(&sb->s_inode_list_lock); + iput(toput_inode); +} + +static int proc_dpages_show(struct seq_file *m, void *v) +{ + iterate_supers((void *)dump_dirtypages_sb, (void *)m); + return 0; +} + +static int proc_dpages_open(struct inode *inode, struct file *filp) +{ + int ret; + struct seq_file *m; + + if (!dirty_pages_lock()) + return -EBUSY; + + if (buf_dirty == NULL || buf_size == 0) { + pr_warn("please allocate buffer before getting dirty pages\n"); + dirty_pages_unlock(); + return -ENOMEM; + } + + ret = single_open(filp, proc_dpages_show, NULL); + if (ret) { + dirty_pages_unlock(); + return ret; + } + + m = (struct seq_file *)filp->private_data; + memset(buf_dirty, 0, buf_size); + m->size = buf_size - (strlen(TERM_STR) + 1); + m->buf = buf_dirty; + + return 0; +} + +static int proc_dpages_release(struct inode *inode, struct file *file) +{ + struct seq_file *m = file->private_data; + + /* we don't want to free the buf */ + m->buf = NULL; + dirty_pages_unlock(); + return single_release(inode, file); +} + +static void free_buf_dirty(void) +{ + if (!buf_dirty) + return; + + vfree(buf_dirty); + buf_dirty = NULL; + buf_size = 0; + WRITE_ONCE(buf_num, 0); +} + +static int proc_buffer_show(struct seq_file *m, void *v) +{ + seq_printf(m, "%lu\n", READ_ONCE(buf_num)); + return 0; +} + +static int proc_buffer_open(struct inode *inode, struct file *filp) +{ + int ret; + + if (((filp->f_flags & O_ACCMODE) != O_RDONLY) && !dirty_pages_lock()) + return -EBUSY; + + ret = single_open(filp, proc_buffer_show, NULL); + if (ret) + dirty_pages_unlock(); + + return ret; +} + +static ssize_t proc_buffer_write(struct file *filp, const char __user *buf, + size_t count, loff_t *offp) +{ + int ret; + unsigned long new_buf_num, new_buf_size; + char *new_buf_dirty; + + ret = kstrtoul_from_user(buf, count, 10, &new_buf_num); + if (ret != 0 || new_buf_num > MAX_BUF_NUM) + return -EINVAL; + + if (new_buf_num == buf_num) + return count; + + if (new_buf_num == 0) { + free_buf_dirty(); + return count; + } + + new_buf_size = PAGE_SIZE * new_buf_num; + new_buf_dirty = vzalloc(new_buf_size); + if (!new_buf_dirty) + return -ENOMEM; + + free_buf_dirty(); + buf_dirty = new_buf_dirty; + buf_size = new_buf_size; + WRITE_ONCE(buf_num, new_buf_num); + + return count; +} + +static int proc_buffer_release(struct inode *inode, struct file *filp) +{ + if ((filp->f_flags & O_ACCMODE) != O_RDONLY) + dirty_pages_unlock(); + return single_release(inode, filp); +} + +static int proc_limit_show(struct seq_file *m, void *v) +{ + seq_printf(m, "%lu\n", READ_ONCE(buf_limit)); + return 0; +} + +static int proc_limit_open(struct inode *inode, struct file *filp) +{ + return single_open(filp, proc_limit_show, NULL); +} + +static ssize_t proc_limit_write(struct file *filp, const char __user *buf, + size_t count, loff_t *offp) +{ + int ret; + unsigned long limit; + + ret = kstrtoul_from_user(buf, count, 10, &limit); + if (ret != 0) + return ret; + + WRITE_ONCE(buf_limit, limit); + + return count; +} + +static const struct proc_ops proc_dpages_operations = { + .proc_open = proc_dpages_open, + .proc_read = seq_read, + .proc_release = proc_dpages_release, +}; + +static const struct proc_ops proc_buffer_operations = { + .proc_open = proc_buffer_open, + .proc_read = seq_read, + .proc_write = proc_buffer_write, + .proc_lseek = seq_lseek, + .proc_release = proc_buffer_release, +}; + +static const struct proc_ops proc_limit_operations = { + .proc_open = proc_limit_open, + .proc_read = seq_read, + .proc_write = proc_limit_write, + .proc_lseek = seq_lseek, + .proc_release = single_release, +}; + +static int __init dpages_proc_init(void) +{ + struct proc_dir_entry *dirty_dir; + + dirty_dir = proc_mkdir(DIRTY_ROOT, NULL); + if (!dirty_dir) + return -ENOMEM; + + if (!proc_create(DIRTY_PAGES, 0440, dirty_dir, &proc_dpages_operations)) + goto fail_pages; + + if (!proc_create(DIRTY_BUFFER_SIZE, 0640, dirty_dir, + &proc_buffer_operations)) + goto fail_switch; + + if (!proc_create(DIRTY_LIMIT, 0640, dirty_dir, &proc_limit_operations)) + goto fail_limit; + + return 0; + +fail_limit: + remove_proc_entry(DIRTY_BUFFER_SIZE, dirty_dir); +fail_switch: + remove_proc_entry(DIRTY_PAGES, dirty_dir); +fail_pages: + remove_proc_entry(DIRTY_ROOT, NULL); + return -ENOMEM; +} + +subsys_initcall(dpages_proc_init); -- 2.39.2

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[PATCH OLK-6.6] fs/dcache.c: avoid panic while lockref of dentry overflow
by Zizhi Wo 09 Jan '24

09 Jan '24

From: yangerkun <yangerkun(a)huawei.com> hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8JDP6 --------------------------- We use lockref for dentry reference without notice that so many negative dentry under one dir can lead to overflow of lockref. This can lead to system crash if we do this under root dir. Since there is not a perfect solution, we just limit max number of dentry count up to INT_MAX / 2. Also, it will cost a lot of time from INT_MAX / 2 to INT_MAX, so we no need to do this under protection of dentry lock. Also, we limit the FILES_MAX to INT_MAX / 2, since a lot open for same file can lead to overflow too. Changelog: v1->v2: add a function to do check / add a Macro to mean INT_MAX / 2 Signed-off-by: yangerkun <yangerkun(a)huawei.com> Signed-off-by: Zizhi Wo <wozizhi(a)huawei.com> --- fs/dcache.c | 32 ++++++++++++++++++++++++++++---- fs/filescontrol.c | 2 +- include/linux/fs.h | 3 +++ 3 files changed, 32 insertions(+), 5 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 25ac74d30bff..7cdd8bbedd1c 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1834,6 +1834,18 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) return dentry; } +static inline bool d_forbid_overflow(struct dentry *dentry) +{ + if (unlikely(d_count(dentry) >= D_COUNT_MAX)) { + shrink_dcache_parent(dentry); + + if (d_count(dentry) >= D_COUNT_MAX) + return false; + } + + return true; +} + /** * d_alloc - allocate a dcache entry * @parent: parent of entry to allocate @@ -1845,9 +1857,15 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) */ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) { - struct dentry *dentry = __d_alloc(parent->d_sb, name); + struct dentry *dentry = NULL; + + if (unlikely(!d_forbid_overflow(parent))) + goto out; + + dentry = __d_alloc(parent->d_sb, name); if (!dentry) - return NULL; + goto out; + spin_lock(&parent->d_lock); /* * don't need child lock because it is not subject @@ -1857,7 +1875,7 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) dentry->d_parent = parent; list_add(&dentry->d_child, &parent->d_subdirs); spin_unlock(&parent->d_lock); - +out: return dentry; } EXPORT_SYMBOL(d_alloc); @@ -1870,11 +1888,17 @@ EXPORT_SYMBOL(d_alloc_anon); struct dentry *d_alloc_cursor(struct dentry * parent) { - struct dentry *dentry = d_alloc_anon(parent->d_sb); + struct dentry *dentry = NULL; + + if (unlikely(!d_forbid_overflow(parent))) + goto out; + + dentry = d_alloc_anon(parent->d_sb); if (dentry) { dentry->d_flags |= DCACHE_DENTRY_CURSOR; dentry->d_parent = dget(parent); } +out: return dentry; } diff --git a/fs/filescontrol.c b/fs/filescontrol.c index 610f13a36962..0947566b9119 100644 --- a/fs/filescontrol.c +++ b/fs/filescontrol.c @@ -27,7 +27,7 @@ #include <linux/sched/signal.h> #include <linux/module.h> -#define FILES_MAX ULONG_MAX +#define FILES_MAX D_COUNT_MAX #define FILES_MAX_STR "max" static bool no_acct; diff --git a/include/linux/fs.h b/include/linux/fs.h index fb5accebdcdf..67c2ac09e700 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -47,6 +47,9 @@ #include <asm/byteorder.h> #include <uapi/linux/fs.h> +#define D_COUNT_MAX (INT_MAX / 2) + + struct backing_dev_info; struct bdi_writeback; struct bio; -- 2.39.2

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