On Thu, 2006-03-09 at 13:22 -0800, anil dahiya wrote: > Hi > on 2.4.21-32(redhat enterprise update 5) when i call kmalloc with > GFP_KERNEL > my system get hangs it hangs.. Anyone can suggest what should i do .. You didn't read the mail that you replied to (and top-quoted BTW)? [....] > Hareesh Nagarajan <hnagar2@xxxxxxxxx> wrote: > On 3/9/06, Mauricio Lin wrote: > > Hi all, > > > > Is it possible to use kmalloc() in schedule() function? > > > > I have used kmalloc to allocate memory in schedule() but it > does not work > > since during the boot the kernel gets frozen. > > kmalloc with the flag GFP_KERNEL can potentially sleep. Which > means, > the resource, which in this case is memory, cannot be > allocated in an > atomic manner, so the kernel can put the requester in a wait > queue, > call schedule(). (and of ! course when the resource is > available, the > requester is woken up.) > > So now inside schedule() you have a call that can sleep, or in > other > words, you have a call that can schedule(). So you see: > > schedule() > kmalloc(...) > schedule() > kmalloc(...) > ... > > This is far from ideal. You will run out of stack, which > inside the > kernel is only 4K. Stay away from kmalloc-ing inside schedule, > or if > you really need to use kmalloc, use it with the flag > GFP_ATOMIC. [...] Bernd -- Firmix Software GmbH http://www.firmix.at/ mobil: +43 664 4416156 fax: +43 1 7890849-55 Embedded Linux Development and Services -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
