CONFIG_DEBUG_PAGEALLOC: Debug page memory allocations

General informations

The Linux kernel configuration item CONFIG_DEBUG_PAGEALLOC has multiple definitions:

Debug page memory allocations found in mm/Kconfig.debug

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Debug page memory allocations
• type: bool
• depends on: ( CONFIG_DEBUG_KERNEL ) && (! CONFIG_HIBERNATION || CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC && ! CONFIG_PPC && ! CONFIG_SPARC )
• defined in mm/Kconfig.debug
• found in Linux kernels: 2.6.30–2.6.39, 3.0–3.19, 4.0–4.20, 5.0–5.19, 6.0–6.11, 6.12-rc+HEAD

Help text

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.

Debug page memory allocations found in arch/m32r/Kconfig.debug

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Debug page memory allocations
• type: bool
• depends on: CONFIG_DEBUG_KERNEL && CONFIG_BROKEN
• defined in arch/m32r/Kconfig.debug
• found in Linux kernels: 2.6.17–2.6.39, 3.0–3.19, 4.0–4.16

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

Debug page memory allocations found in arch/x86/Kconfig.debug

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Debug page memory allocations
• type: bool
• depends on: CONFIG_DEBUG_KERNEL
• defined in arch/x86/Kconfig.debug
• found in Linux kernels: 2.6.24–2.6.29

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

Debug page memory allocations found in arch/sparc/Kconfig.debug

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Debug page memory allocations
• type: bool
• depends on: CONFIG_SPARC64 && CONFIG_DEBUG_KERNEL && ! CONFIG_HIBERNATION
• defined in arch/sparc/Kconfig.debug
• found in Linux kernels: 2.6.29

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

Debug page memory allocations found in arch/s390/Kconfig.debug

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Debug page memory allocations
• type: bool
• depends on: CONFIG_DEBUG_KERNEL
• defined in arch/s390/Kconfig.debug
• found in Linux kernels: 2.6.25–2.6.29

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a slowdown, but helps to find certain types of memory corruptions.

Debug page memory allocations found in arch/powerpc/Kconfig.debug

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Debug page memory allocations
• type: bool
• depends on: CONFIG_DEBUG_KERNEL && ! CONFIG_HIBERNATION
• defined in arch/powerpc/Kconfig.debug
• found in Linux kernels: 2.6.22–2.6.29

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

Debug page memory allocations found in arch/sparc64/Kconfig.debug

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Debug page memory allocations
• type: bool
• depends on: CONFIG_DEBUG_KERNEL && ! CONFIG_HIBERNATION
• defined in arch/sparc64/Kconfig.debug
• found in Linux kernels: 2.6.17–2.6.28

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

Debug page memory allocations found in arch/i386/Kconfig.debug

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Debug page memory allocations
• type: bool
• depends on: CONFIG_DEBUG_KERNEL && ! CONFIG_HIBERNATION && ! CONFIG_HUGETLBFS
• defined in arch/i386/Kconfig.debug
• found in Linux kernels: 2.6.17–2.6.23

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

Page alloc debugging found in arch/sparc64/Kconfig.debug

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Page alloc debugging
• type: bool
• depends on: CONFIG_DEBUG_KERNEL && ! CONFIG_SOFTWARE_SUSPEND
• defined in arch/sparc64/Kconfig.debug
• found in Linux kernels: 2.6.14–2.6.16

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

Page alloc debugging found in arch/m32r/Kconfig.debug

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Page alloc debugging
• type: bool
• depends on: CONFIG_DEBUG_KERNEL && CONFIG_BROKEN
• defined in arch/m32r/Kconfig.debug
• found in Linux kernels: 2.6.10–2.6.16

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

Page alloc debugging found in arch/i386/Kconfig.debug

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Page alloc debugging
• type: bool
• depends on: CONFIG_DEBUG_KERNEL && ! CONFIG_SOFTWARE_SUSPEND
• defined in arch/i386/Kconfig.debug
• found in Linux kernels: 2.6.9–2.6.16

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

Page alloc debugging found in arch/frv/Kconfig.debug

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Page alloc debugging
• type: bool
• depends on: CONFIG_DEBUG_KERNEL
• defined in arch/frv/Kconfig.debug
• found in Linux kernels: 2.6.12–2.6.15

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

Page alloc debugging found in arch/frv/Kconfig

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Page alloc debugging
• type: bool
• depends on: CONFIG_DEBUG_KERNEL
• defined in arch/frv/Kconfig
• found in Linux kernels: 2.6.11

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

Page alloc debugging found in arch/m32r/Kconfig

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Page alloc debugging
• type: bool
• depends on: CONFIG_DEBUG_KERNEL
• defined in arch/m32r/Kconfig
• found in Linux kernels: 2.6.9

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

Page alloc debugging found in arch/i386/Kconfig

The configuration item CONFIG_DEBUG_PAGEALLOC:

• prompt: Page alloc debugging
• type: bool
• depends on: CONFIG_DEBUG_KERNEL
• defined in arch/i386/Kconfig
• found in Linux kernels: 2.5.75, 2.6.0–2.6.8

Help text

Unmap pages from the kernel linear mapping after free_pages(). This results in a large slowdown, but helps to find certain types of memory corruptions.

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