Linux system errors
Linux 11 Signal 11 (SIGSEGV) memory fault or Errno 11 (EAGAIN / EWOULDBLOCK) resource unavailable
Reviewed for reference consistency: April 11, 2026
Signal 11 (SIGSEGV) memory fault or Errno 11 (EAGAIN / EWOULDBLOCK) resource unavailable
What 11 Means
The 11 error on the Linux system errors indicates signal 11 (sigsegv) memory fault or errno 11 (eagain / ewouldblock) resource unavailable. This typically occurs due to dereferencing a null, invalid, or freed memory pointer (signal 11 / sigsegv).
In Linux systems, Error 11 refers to two distinct technical mechanisms depending on the reporting subsystem: kernel Signal 11 (SIGSEGV) representing an invalid memory access crash, or C library Errno 11 (EAGAIN / EWOULDBLOCK) indicating a non-blocking operation or temporary resource constraint.
How to fix 11
General informational guidance, not professional advice. Commands can affect your system or data — back up first and proceed at your own risk. FixerCode is an independent reference, not affiliated with any vendor mentioned.
Check kernel logs to confirm SIGSEGV vs resource exhaustion
Inspect dmesg output for 'segfault' entries to verify a Signal 11 crash, or look for 'Resource temporarily unavailable' for an Errno 11 event.
dmesg -T | grep -iE 'segfault|signal 11|eagain'Inspect system process and thread limits for EAGAIN errors
If experiencing 'fork: Resource temporarily unavailable' (EAGAIN), check the user process limits and system-wide thread limits.
ulimit -u && sysctl kernel.threads-max kernel.pid-maxCapture a backtrace with GDB for SIGSEGV crashes
Run the faulting compiled application under gdb and obtain a backtrace to isolate the invalid memory access function and line number.
gdb --args ./your_program run btEnable core dumps for post-mortem crash inspection
Configure core dumps to capture process state at the moment of SIGSEGV signal delivery without needing live reproduction.
ulimit -c unlimited coredumpctl gdb
Technical Background
Linux Error 11 requires distinguishing between two underlying subsystems: kernel Signal 11 (SIGSEGV) and system call return code Errno 11 (EAGAIN / EWOULDBLOCK). Identifying which mechanism generated the error is the key first step in diagnosing log outputs.
Signal 11 (SIGSEGV) represents an unrecoverable memory fault raised when a process accesses memory not mapped to its address space or attempts forbidden memory operations. Shells and CI pipelines report this termination as exit code 139 (128 + 11). Low-level debugger backtraces and dmesg kernel logs classify it as signal 11.
Errno 11 (EAGAIN / EWOULDBLOCK), by contrast, is a non-fatal status returned by system calls such as read, write, connect, or fork. It signifies that an operation on a non-blocking descriptor cannot complete immediately or that system limits (such as nproc or max threads) temporarily prevent creating new resources.
Common Causes
- Dereferencing a null, invalid, or freed memory pointer (Signal 11 / SIGSEGV)
- Non-blocking I/O socket read/write operation when data is not ready (Errno 11 / EAGAIN)
- Reaching user process or thread creation limits like nproc during fork (Errno 11 / EAGAIN)
- Buffer overflow or out-of-bounds memory access in compiled C/C++/Rust code
Typical Scenarios
- A compiled C/C++ or Rust application crashes immediately due to a null pointer dereference, generating a SIGSEGV signal 11 and exiting with shell status 139
- A native library extension loaded by Python, Java, or Node.js triggers memory corruption, causing the host process to terminate with signal 11
- An application fails during process creation with 'EAGAIN: fork: Resource temporarily unavailable' because the max user process limit (uproc/nproc) was reached
- A high-concurrency network service receives EAGAIN / EWOULDBLOCK on a non-blocking socket when attempting to read before data arrives
What to Know
When evaluating Error 11 in Linux logs, verify whether the event represents a process crash from Signal 11 (SIGSEGV / exit code 139) or a system call status from Errno 11 (EAGAIN / EWOULDBLOCK resource exhaustion). Signal 11 means memory access violation, whereas Errno 11 indicates temporary resource unavailability.
Frequently Asked Questions
Common questions about Linux 11 error
Signal 11 (SIGSEGV) is a kernel termination signal sent when a process attempts illegal memory access. Errno 11 (EAGAIN/EWOULDBLOCK) is a system call return code telling a running process that a requested resource is temporarily busy or unavailable.
Linux shells report signal-terminated processes by adding 128 to the signal number. For Signal 11 (SIGSEGV), adding 128 yields 139 (128 + 11 = 139).
Kernel logs (`dmesg`) showing 'segfault at ... ip ...' indicate Signal 11. System log messages stating 'Resource temporarily unavailable' or syscall returns of -1 with errno 11 indicate EAGAIN.
Related Error Codes
Process Killed — the process was terminated by a SIGKILL signal
Exit code 139 — a segmentation fault (SIGSEGV, signal 11) killed the process
Out of Memory (ENOMEM) — the kernel cannot allocate the requested amount of memory
Invalid Exit Argument — script exited with an out-of-range status or terminated by a signal
Related Errors From Other Categories
Similar error codes documented across different platforms and systems
Git's internal object database is missing or corrupted.
The operating system denied Git's request for more RAM during a heavy operation.
Git detected corruption inside one of its compressed data bundles (packfiles).
An uncompressed file in Git's internal database has an invalid checksum or zero bytes.