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Diffstat (limited to 'Documentation/filesystems/proc.rst')
| -rw-r--r-- | Documentation/filesystems/proc.rst | 138 |
1 files changed, 124 insertions, 14 deletions
diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 104c6d047d9b..09f0aed5a08b 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -48,6 +48,7 @@ fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009 3.11 /proc/<pid>/patch_state - Livepatch patch operation state 3.12 /proc/<pid>/arch_status - Task architecture specific information 3.13 /proc/<pid>/fd - List of symlinks to open files + 3.14 /proc/<pid/ksm_stat - Information about the process's ksm status. 4 Configuring procfs 4.1 Mount options @@ -443,6 +444,15 @@ is not associated with a file: or if empty, the mapping is anonymous. +Starting with 6.11 kernel, /proc/PID/maps provides an alternative +ioctl()-based API that gives ability to flexibly and efficiently query and +filter individual VMAs. This interface is binary and is meant for more +efficient and easy programmatic use. `struct procmap_query`, defined in +linux/fs.h UAPI header, serves as an input/output argument to the +`PROCMAP_QUERY` ioctl() command. See comments in linus/fs.h UAPI header for +details on query semantics, supported flags, data returned, and general API +usage information. + The /proc/PID/smaps is an extension based on maps, showing the memory consumption for each of the process's mappings. For each mapping (aka Virtual Memory Area, or VMA) there is a series of lines such as the following:: @@ -475,14 +485,15 @@ Memory Area, or VMA) there is a series of lines such as the following:: THPeligible: 0 VmFlags: rd ex mr mw me dw -The first of these lines shows the same information as is displayed for the -mapping in /proc/PID/maps. Following lines show the size of the mapping -(size); the size of each page allocated when backing a VMA (KernelPageSize), -which is usually the same as the size in the page table entries; the page size -used by the MMU when backing a VMA (in most cases, the same as KernelPageSize); -the amount of the mapping that is currently resident in RAM (RSS); the -process' proportional share of this mapping (PSS); and the number of clean and -dirty shared and private pages in the mapping. +The first of these lines shows the same information as is displayed for +the mapping in /proc/PID/maps. Following lines show the size of the +mapping (size); the size of each page allocated when backing a VMA +(KernelPageSize), which is usually the same as the size in the page table +entries; the page size used by the MMU when backing a VMA (in most cases, +the same as KernelPageSize); the amount of the mapping that is currently +resident in RAM (RSS); the process's proportional share of this mapping +(PSS); and the number of clean and dirty shared and private pages in the +mapping. The "proportional set size" (PSS) of a process is the count of pages it has in memory, where each page is divided by the number of processes sharing it. @@ -570,7 +581,8 @@ encoded manner. The codes are the following: mt arm64 MTE allocation tags are enabled um userfaultfd missing tracking uw userfaultfd wr-protect tracking - ss shadow stack page + ss shadow/guarded control stack page + sl sealed == ======================================= Note that there is no guarantee that every flag and associated mnemonic will @@ -688,6 +700,7 @@ files are there, and which are missing. ============ =============================================================== File Content ============ =============================================================== + allocinfo Memory allocations profiling information apm Advanced power management info bootconfig Kernel command line obtained from boot config, and, if there were kernel parameters from the @@ -953,6 +966,35 @@ also be allocatable although a lot of filesystem metadata may have to be reclaimed to achieve this. +allocinfo +~~~~~~~~~ + +Provides information about memory allocations at all locations in the code +base. Each allocation in the code is identified by its source file, line +number, module (if originates from a loadable module) and the function calling +the allocation. The number of bytes allocated and number of calls at each +location are reported. The first line indicates the version of the file, the +second line is the header listing fields in the file. + +Example output. + +:: + + > tail -n +3 /proc/allocinfo | sort -rn + 127664128 31168 mm/page_ext.c:270 func:alloc_page_ext + 56373248 4737 mm/slub.c:2259 func:alloc_slab_page + 14880768 3633 mm/readahead.c:247 func:page_cache_ra_unbounded + 14417920 3520 mm/mm_init.c:2530 func:alloc_large_system_hash + 13377536 234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs + 11718656 2861 mm/filemap.c:1919 func:__filemap_get_folio + 9192960 2800 kernel/fork.c:307 func:alloc_thread_stack_node + 4206592 4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable + 4136960 1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start + 3940352 962 mm/memory.c:4214 func:alloc_anon_folio + 2894464 22613 fs/kernfs/dir.c:615 func:__kernfs_new_node + ... + + meminfo ~~~~~~~ @@ -1110,8 +1152,8 @@ KernelStack PageTables Memory consumed by userspace page tables SecPageTables - Memory consumed by secondary page tables, this currently - currently includes KVM mmu allocations on x86 and arm64. + Memory consumed by secondary page tables, this currently includes + KVM mmu and IOMMU allocations on x86 and arm64. NFS_Unstable Always zero. Previous counted pages which had been written to the server, but has not been committed to stable storage. @@ -1899,8 +1941,8 @@ For more information on mount propagation see: These files provide a method to access a task's comm value. It also allows for a task to set its own or one of its thread siblings comm value. The comm value is limited in size compared to the cmdline value, so writing anything longer -then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated -comm value. +then the kernel's TASK_COMM_LEN (currently 16 chars, including the NUL +terminator) will result in a truncated comm value. 3.7 /proc/<pid>/task/<tid>/children - Information about task children @@ -2192,6 +2234,74 @@ The number of open files for the process is stored in 'size' member of stat() output for /proc/<pid>/fd for fast access. ------------------------------------------------------- +3.14 /proc/<pid/ksm_stat - Information about the process's ksm status +--------------------------------------------------------------------- +When CONFIG_KSM is enabled, each process has this file which displays +the information of ksm merging status. + +Example +~~~~~~~ + +:: + + / # cat /proc/self/ksm_stat + ksm_rmap_items 0 + ksm_zero_pages 0 + ksm_merging_pages 0 + ksm_process_profit 0 + ksm_merge_any: no + ksm_mergeable: no + +Description +~~~~~~~~~~~ + +ksm_rmap_items +^^^^^^^^^^^^^^ + +The number of ksm_rmap_item structures in use. The structure +ksm_rmap_item stores the reverse mapping information for virtual +addresses. KSM will generate a ksm_rmap_item for each ksm-scanned page of +the process. + +ksm_zero_pages +^^^^^^^^^^^^^^ + +When /sys/kernel/mm/ksm/use_zero_pages is enabled, it represent how many +empty pages are merged with kernel zero pages by KSM. + +ksm_merging_pages +^^^^^^^^^^^^^^^^^ + +It represents how many pages of this process are involved in KSM merging +(not including ksm_zero_pages). It is the same with what +/proc/<pid>/ksm_merging_pages shows. + +ksm_process_profit +^^^^^^^^^^^^^^^^^^ + +The profit that KSM brings (Saved bytes). KSM can save memory by merging +identical pages, but also can consume additional memory, because it needs +to generate a number of rmap_items to save each scanned page's brief rmap +information. Some of these pages may be merged, but some may not be abled +to be merged after being checked several times, which are unprofitable +memory consumed. + +ksm_merge_any +^^^^^^^^^^^^^ + +It specifies whether the process's 'mm is added by prctl() into the +candidate list of KSM or not, and if KSM scanning is fully enabled at +process level. + +ksm_mergeable +^^^^^^^^^^^^^ + +It specifies whether any VMAs of the process''s mms are currently +applicable to KSM. + +More information about KSM can be found in +Documentation/admin-guide/mm/ksm.rst. + Chapter 4: Configuring procfs ============================= @@ -2221,7 +2331,7 @@ arguments are now protected against local eavesdroppers. hidepid=invisible or hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other users. It doesn't mean that it hides a fact whether a process with a specific pid value exists (it can be learned by other means, e.g. -by "kill -0 $PID"), but it hides process' uid and gid, which may be learned by +by "kill -0 $PID"), but it hides process's uid and gid, which may be learned by stat()'ing /proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering information about running processes, whether some daemon runs with elevated privileges, whether other user runs some sensitive program, whether |