The previous 2.4 Linux kernel maintainer, Marcelo Tossati, resurrected a discussion on adding support for out of memory notifications to the Linux kernel. He explained, "AIX contains the SIGDANGER signal to notify applications to free up some unused cached memory," then noting, "there have been a few discussions on implementing such an idea on Linux, but nothing concrete has been achieved." In a request for discussion, Marcelo added, "on the kernel side Rik suggested two notification points: 'about to swap' (for desktop scenarios) and 'about to OOM' (for embedded-like scenarios)." Rik van Riel explained:

"The first threshold - 'we are about to swap' - means the application frees memory that it can. Eg. free()d memory that glibc has not yet given back to the kernel, or JVM running the garbage collector, or ...

"The second threshold - 'we are out of memory' - means that the first approach has failed and the system needs to do something else. On an embedded system, I would expect some application to exit or maybe restart itself."

Willy Tarreau replaced Marcelo Tosatti [interview] as the 2.4 stable Linux kernel maintainer in August of 2006 [story]. In response to a series of compilation fixes sent to the lkml by Mariusz Kozlowski, Willy suggested that all patches would be postponed until 2.4.34 is released. He suggested that in the interum the appropriate subsystem maintainers should be contacted to determine whether or not each of the patches should be merged, "we would merge the accepted patches and those without any reply which we consider relevant early in the 35-pre cycle so that people have some time to inform us about the potential conflicts they encounter."

Willy went on to describe how to determine who maintains each of the files, "check for the maintainer in the files themselves, or in the MAINTAINERS file. As a rule of thumb, if a file has not changed in the last 3 years and its maintainer is not one of the active ones you regularly see posting on LKML, then there are great chances that the file is unmaintained." He continued, "generally, the core subsystems (network, filesystems, archs, ...) are still well maintained by people who *really want* to validate the patches before forwarding them upstream." He went on to note, "they're all busy, so make the question simple enough so that they can quickly reply with ACK/NACK/QUEUED. Keep me CCed so that you don't have to forward me the response. Generally, they will reply within one week." Willy concluded, "if there's no easily identifiable maintainer anymore, or if some maintainers don't reply, then it becomes my job."

Marcelo Tosatti became the maintainer of the 2.4 stable kernel when he was 18 years old in November of 2001. His first kernel release was 2.4.16 on November 26'th which very quickly followed the earlier 2.4.15 to address an issue with filesystem corruption. Two years later, he has recently released 2.4.23 and plans to soon put the 2.4 stable kernel into maintenance mode, only addressing bugs and security issues.

Living in Brazil, Marcelo currently works for Cyclades Corporation. In this interview he looks at how he became the 2.4 maintainer, the challenges involved, and brings us up to date with the current status of the 2.4 kernel.

Kerneltrap has spoken with Linux guru Alan Cox. He is perhaps the second most influential Linux kernel hacker, next only to Linus. In this interview he talks about himself, his history with computers and Linux, working for Red Hat, Marcello and the 2.4 kernel, the DMCA, the future of Linux and much more.