Skip to content



memfd_create - create an anonymous file.


The memfd_create() system call creates an anonymous file and returns a file descriptor that refers to it. The file behaves like a regular file and can be modified, mapped, and can also grow as required. This is typically used for in-memory storage without the need for a backing file on the filesystem, thus providing a mechanism for efficient inter-process communication and temporary storage.

Files created using memfd_create() are automatically removed once the last reference to them is closed, ensuring they don't persist beyond their required lifespan.


  • name:const char *[U] - An optional name for the file, mainly used for debugging purposes.
  • flags:unsigned int[K] - Flags to modify the behavior. Notable flags include:
    • MFD_CLOEXEC: Set the close-on-exec flag for the new file descriptor.
    • MFD_ALLOW_SEALING: Allow the file to be sealed, preventing further modifications.

Available Tags

  • K - Originated from kernel-space.
  • U - Originated from user space.
  • TOCTOU - Vulnerable to TOCTOU (time of check, time of use).
  • OPT - Optional argument - might not always be available (passed with null value).




Tracepoint (through sys_enter).


To monitor and trace when the memfd_create() system call is invoked, capturing details about the file's creation, its name, and any flags set.

Example Use Case

Implementing a high-performance caching mechanism where data is stored in memory but accessed through a file descriptor. This can be used in scenarios where data needs to be shared between processes or stored temporarily without the overhead of disk I/O.


Since memfd_create() provides an in-memory file storage mechanism, overuse without proper monitoring could lead to excessive memory consumption. Moreover, if not appropriately managed, this could be exploited by malicious actors to create a denial-of-service condition.

  • ftruncate() - To resize the in-memory file.
  • mmap() - To map the file into the process's address space.

This document was automatically generated by OpenAI and reviewed by a Human.