> I have a kernel customization which closes all file descriptors for > this process just > before starting its core dump. This way any file locks held by this > process can be > released automatically inside kernel before core dump. In some cases closing the file descriptors will have side effects on the core dump (consider mmap() objects). There are also users who rely upon pipe() returning EOF as a way of detecting a process has exited (closing the other end of the pipe). The pipe case is already racy agains the exit completing so ought not to matter. > I am wondering whether this kernel customization can cause any side effects for > the user land process memory state? I roughly went through mmap/socket/fifo/ > pipe/sysv-ipc code, it looks closing files from inside kernel doesn't > change user > land process's memory content. However I am not sure, so I would like to ask > help and confirm from you. If you drop the locks and close the file descriptors but don't drop the mmap() references at that point then as far as I can see on a first think you ought to be ok. The last reference to an mmap() object would then remain however - so mmap() objects would be cleaned up and the final release happen after the core dump finished. The other quick hack for this of course is to make the app use sigaction to catch the core dumping signals except SIGABRT and close the file descriptors and call abort(). Alan -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
