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| -rw-r--r-- | mm/Kconfig.debug | 286 |
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diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug new file mode 100644 index 0000000000..018a5bd2f5 --- /dev/null +++ b/mm/Kconfig.debug @@ -0,0 +1,286 @@ +# SPDX-License-Identifier: GPL-2.0-only +config PAGE_EXTENSION + bool "Extend memmap on extra space for more information on page" + help + Extend memmap on extra space for more information on page. This + could be used for debugging features that need to insert extra + field for every page. This extension enables us to save memory + by not allocating this extra memory according to boottime + configuration. + +config DEBUG_PAGEALLOC + bool "Debug page memory allocations" + depends on DEBUG_KERNEL + depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC + select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC + help + Unmap pages from the kernel linear mapping after free_pages(). + Depending on runtime enablement, this results in a small or large + slowdown, but helps to find certain types of memory corruption. + + Also, the state of page tracking structures is checked more often as + pages are being allocated and freed, as unexpected state changes + often happen for same reasons as memory corruption (e.g. double free, + use-after-free). The error reports for these checks can be augmented + with stack traces of last allocation and freeing of the page, when + PAGE_OWNER is also selected and enabled on boot. + + For architectures which don't enable ARCH_SUPPORTS_DEBUG_PAGEALLOC, + fill the pages with poison patterns after free_pages() and verify + the patterns before alloc_pages(). Additionally, this option cannot + be enabled in combination with hibernation as that would result in + incorrect warnings of memory corruption after a resume because free + pages are not saved to the suspend image. + + By default this option will have a small overhead, e.g. by not + allowing the kernel mapping to be backed by large pages on some + architectures. Even bigger overhead comes when the debugging is + enabled by DEBUG_PAGEALLOC_ENABLE_DEFAULT or the debug_pagealloc + command line parameter. + +config DEBUG_PAGEALLOC_ENABLE_DEFAULT + bool "Enable debug page memory allocations by default?" + depends on DEBUG_PAGEALLOC + help + Enable debug page memory allocations by default? This value + can be overridden by debug_pagealloc=off|on. + +config DEBUG_SLAB + bool "Debug slab memory allocations" + depends on DEBUG_KERNEL && SLAB + help + Say Y here to have the kernel do limited verification on memory + allocation as well as poisoning memory on free to catch use of freed + memory. This can make kmalloc/kfree-intensive workloads much slower. + +config SLUB_DEBUG + default y + bool "Enable SLUB debugging support" if EXPERT + depends on SLUB && SYSFS && !SLUB_TINY + select STACKDEPOT if STACKTRACE_SUPPORT + help + SLUB has extensive debug support features. Disabling these can + result in significant savings in code size. While /sys/kernel/slab + will still exist (with SYSFS enabled), it will not provide e.g. cache + validation. + +config SLUB_DEBUG_ON + bool "SLUB debugging on by default" + depends on SLUB && SLUB_DEBUG + select STACKDEPOT_ALWAYS_INIT if STACKTRACE_SUPPORT + default n + help + Boot with debugging on by default. SLUB boots by default with + the runtime debug capabilities switched off. Enabling this is + equivalent to specifying the "slub_debug" parameter on boot. + There is no support for more fine grained debug control like + possible with slub_debug=xxx. SLUB debugging may be switched + off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying + "slub_debug=-". + +config PAGE_OWNER + bool "Track page owner" + depends on DEBUG_KERNEL && STACKTRACE_SUPPORT + select DEBUG_FS + select STACKTRACE + select STACKDEPOT + select PAGE_EXTENSION + help + This keeps track of what call chain is the owner of a page, may + help to find bare alloc_page(s) leaks. Even if you include this + feature on your build, it is disabled in default. You should pass + "page_owner=on" to boot parameter in order to enable it. Eats + a fair amount of memory if enabled. See tools/mm/page_owner_sort.c + for user-space helper. + + If unsure, say N. + +config PAGE_TABLE_CHECK + bool "Check for invalid mappings in user page tables" + depends on ARCH_SUPPORTS_PAGE_TABLE_CHECK + depends on EXCLUSIVE_SYSTEM_RAM + select PAGE_EXTENSION + help + Check that anonymous page is not being mapped twice with read write + permissions. Check that anonymous and file pages are not being + erroneously shared. Since the checking is performed at the time + entries are added and removed to user page tables, leaking, corruption + and double mapping problems are detected synchronously. + + If unsure say "n". + +config PAGE_TABLE_CHECK_ENFORCED + bool "Enforce the page table checking by default" + depends on PAGE_TABLE_CHECK + help + Always enable page table checking. By default the page table checking + is disabled, and can be optionally enabled via page_table_check=on + kernel parameter. This config enforces that page table check is always + enabled. + + If unsure say "n". + +config PAGE_POISONING + bool "Poison pages after freeing" + help + Fill the pages with poison patterns after free_pages() and verify + the patterns before alloc_pages. The filling of the memory helps + reduce the risk of information leaks from freed data. This does + have a potential performance impact if enabled with the + "page_poison=1" kernel boot option. + + Note that "poison" here is not the same thing as the "HWPoison" + for CONFIG_MEMORY_FAILURE. This is software poisoning only. + + If you are only interested in sanitization of freed pages without + checking the poison pattern on alloc, you can boot the kernel with + "init_on_free=1" instead of enabling this. + + If unsure, say N + +config DEBUG_PAGE_REF + bool "Enable tracepoint to track down page reference manipulation" + depends on DEBUG_KERNEL + depends on TRACEPOINTS + help + This is a feature to add tracepoint for tracking down page reference + manipulation. This tracking is useful to diagnose functional failure + due to migration failures caused by page reference mismatches. Be + careful when enabling this feature because it adds about 30 KB to the + kernel code. However the runtime performance overhead is virtually + nil until the tracepoints are actually enabled. + +config DEBUG_RODATA_TEST + bool "Testcase for the marking rodata read-only" + depends on STRICT_KERNEL_RWX + help + This option enables a testcase for the setting rodata read-only. + +config ARCH_HAS_DEBUG_WX + bool + +config DEBUG_WX + bool "Warn on W+X mappings at boot" + depends on ARCH_HAS_DEBUG_WX + depends on MMU + select PTDUMP_CORE + help + Generate a warning if any W+X mappings are found at boot. + + This is useful for discovering cases where the kernel is leaving W+X + mappings after applying NX, as such mappings are a security risk. + + Look for a message in dmesg output like this: + + <arch>/mm: Checked W+X mappings: passed, no W+X pages found. + + or like this, if the check failed: + + <arch>/mm: Checked W+X mappings: failed, <N> W+X pages found. + + Note that even if the check fails, your kernel is possibly + still fine, as W+X mappings are not a security hole in + themselves, what they do is that they make the exploitation + of other unfixed kernel bugs easier. + + There is no runtime or memory usage effect of this option + once the kernel has booted up - it's a one time check. + + If in doubt, say "Y". + +config GENERIC_PTDUMP + bool + +config PTDUMP_CORE + bool + +config PTDUMP_DEBUGFS + bool "Export kernel pagetable layout to userspace via debugfs" + depends on DEBUG_KERNEL + depends on DEBUG_FS + depends on GENERIC_PTDUMP + select PTDUMP_CORE + help + Say Y here if you want to show the kernel pagetable layout in a + debugfs file. This information is only useful for kernel developers + who are working in architecture specific areas of the kernel. + It is probably not a good idea to enable this feature in a production + kernel. + + If in doubt, say N. + +config HAVE_DEBUG_KMEMLEAK + bool + +config DEBUG_KMEMLEAK + bool "Kernel memory leak detector" + depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK + select DEBUG_FS + select STACKTRACE if STACKTRACE_SUPPORT + select KALLSYMS + select CRC32 + select STACKDEPOT + select STACKDEPOT_ALWAYS_INIT if !DEBUG_KMEMLEAK_DEFAULT_OFF + help + Say Y here if you want to enable the memory leak + detector. The memory allocation/freeing is traced in a way + similar to the Boehm's conservative garbage collector, the + difference being that the orphan objects are not freed but + only shown in /sys/kernel/debug/kmemleak. Enabling this + feature will introduce an overhead to memory + allocations. See Documentation/dev-tools/kmemleak.rst for more + details. + + Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances + of finding leaks due to the slab objects poisoning. + + In order to access the kmemleak file, debugfs needs to be + mounted (usually at /sys/kernel/debug). + +config DEBUG_KMEMLEAK_MEM_POOL_SIZE + int "Kmemleak memory pool size" + depends on DEBUG_KMEMLEAK + range 200 1000000 + default 16000 + help + Kmemleak must track all the memory allocations to avoid + reporting false positives. Since memory may be allocated or + freed before kmemleak is fully initialised, use a static pool + of metadata objects to track such callbacks. After kmemleak is + fully initialised, this memory pool acts as an emergency one + if slab allocations fail. + +config DEBUG_KMEMLEAK_DEFAULT_OFF + bool "Default kmemleak to off" + depends on DEBUG_KMEMLEAK + help + Say Y here to disable kmemleak by default. It can then be enabled + on the command line via kmemleak=on. + +config DEBUG_KMEMLEAK_AUTO_SCAN + bool "Enable kmemleak auto scan thread on boot up" + default y + depends on DEBUG_KMEMLEAK + help + Depending on the cpu, kmemleak scan may be cpu intensive and can + stall user tasks at times. This option enables/disables automatic + kmemleak scan at boot up. + + Say N here to disable kmemleak auto scan thread to stop automatic + scanning. Disabling this option disables automatic reporting of + memory leaks. + + If unsure, say Y. + +config PER_VMA_LOCK_STATS + bool "Statistics for per-vma locks" + depends on PER_VMA_LOCK + help + Say Y here to enable success, retry and failure counters of page + faults handled under protection of per-vma locks. When enabled, the + counters are exposed in /proc/vmstat. This information is useful for + kernel developers to evaluate effectiveness of per-vma locks and to + identify pathological cases. Counting these events introduces a small + overhead in the page fault path. + + If in doubt, say N. |