On Wed, 6 Jun 2007 09:30:53 -0700 William Lee Irwin III <[EMAIL PROTECTED]> wrote:
> On Wed, Jun 06, 2007 at 02:07:37AM -0700, Andrew Morton wrote: > > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.22-rc4/2.6.22-rc4-mm1/ > > - Somebody broke it on my powerpc G5, but I didn't have time to do yet > > another bisection yet. > > - There's a lengthy patch series here from Nick which attempts to address > > the longstanding pagefault-vs-buffered-write deadlock. > > A great shower of filesystems were broken and have been disabled with > > CONFIG_BROKEN. This includes reiser4. > > - Complex patches which eliminate the kernel's fixed size limit on the > > command-line length. These break nommu builds. > > Someone remind me what the pagefault vs. buffered write deadlock is. generic_file_write() does lock_page(), then copies the user's data into pagecache. If that copy_from_user() encounters a major fault and the page is not uptodate, the pagefault handler does lock_page() and deadlocks. It requires that the user be writ()ing from a mmap of the page back into the same page, which is weird. The kernel tries to prefault the page to avoid the copy_from_user() fault, but there are ways in whcih that can be defeated (super memory pressure, malicious fadvise() from a second thread, etc). > Something brings down i386/qemu before even earlyprintk can handle. > > Bisection has narrowed it down to patch 1140 after everything got > renumbered by peterz' fix for mm-variable-length-argument-support.patch, > namely containersv10-make-cpusets-a-client-of-containers.patch erk. A step-by-step how-to-make-this-happen might help if poss, please. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
