memory problem related to squashfs

Squashfs is a compressed filesystem for Linux. If you want more author of Squashfs :-)

This is normal behaviour for Linux. Linux has three caches which are involved in filesystem reading: the page cache, the buffer cache and the dentry (directory entry) cache. As files are read, Linux caches read information in these caches.

These caches use unallocated free memory. The memory used for the caches doesn't become unavailable for program use, in low-memory situations Linux will shrink these caches releasing the memory.

The used memory will be returned when Linux needs it for other uses.

Linux RAM filesystems (i.e. tmpfs) store their data inside the caches as locked data (so they cannot be flushed). Reading such filesystems do not pull data into the caches because it is already there.

The logging data being described is the logging data produced when Squashfs is entered to read filesystem (page) data. In the second and third cases the file read is satisfied from the page cache, and so Squashfs isn't re-entered to read the data, and it therefore doesn't generate any additional logging data.

This is entirely normal behaviour.

As previously mentioned, this is normal Linux behaviour. It is such a central part of the design of Linux that it is very hard to disable it. As the data used for the caches is returned when required, there is no reason why you would want to disable it either.

Phillip Lougher