From mboxrd@z Thu Jan 1 00:00:00 1970 From: Valdis.Kletnieks@vt.edu (Valdis.Kletnieks at vt.edu) Date: Wed, 25 Mar 2015 13:25:04 -0400 Subject: Question about switch_mm function In-Reply-To: Your message of "Wed, 25 Mar 2015 21:35:22 +0530." References: Message-ID: <6084.1427304304@turing-police.cc.vt.edu> To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org On Wed, 25 Mar 2015 21:35:22 +0530, Sreejith M M said: > > This code is handling context switch from a kernel thread back to user mode > > thread so TLB entries are invalid translation for user mode thread and do > > not correspond to user process pgd. It is Master kernel page table > > translation as a result of kernel thread execution. > > > > -Rajat > Hi Rajat, > > If that is the case, why this code is put under CONFIG_SMP switch? Vastly simplified because I'm lazy :) If you look at the code, it's poking the status on *other* CPUs. That's why the cpumask() stuff. If you're on a single execution unit, you don't have to tell the other CPU about the change in state, because there isn't an other CPU. -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 848 bytes Desc: not available Url : http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20150325/94977dc2/attachment.bin