On Tue, May 06, 2014 at 02:51:24PM -0700, Linus Torvalds wrote: > On Tue, May 6, 2014 at 2:35 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Tue, 6 May 2014 17:37:24 +0300 "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> wrote: > > > >> This patchset replaces the syscall with emulation which creates new VMA on > >> each remap and remove code to support non-linear mappings. > >> > >> Nonlinear mappings are pain to support and it seems there's no legitimate > >> use-cases nowadays since 64-bit systems are widely available. > >> > >> It's not yet ready to apply. Just to give rough idea of what can we get if > >> we'll deprecated remap_file_pages(). > >> > >> I need to split patches properly and write correct commit messages. And there's > >> still code to remove. > > > > hah. That's bold. It would be great if we can get away with this. > > > > Do we have any feeling for who will be impacted by this and how badly? > > I *would* love to get rid of the nonlinear mappings, but I really have > zero visibility into who ended up using it. I assume it's a "Oracle on > 32-bit x86" kind of thing. There're funny PyPy people who wants to use remap_file_pages() in new code to build software transaction memory[1]. It sounds just crazy to me. [1] https://lwn.net/Articles/587923/ > I think this is more of a distro question. Plus perhaps an early patch > to just add a warning first so that we can see who it triggers for? Something like this? >From 0371f9b74aa2542e3e85682552cc1b11412f3b0b Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Date: Wed, 7 May 2014 01:52:12 +0300 Subject: [PATCH] mm: mark remap_file_pages() syscall as deprecated remap_file_pages(2) was invented to be able efficiently map parts of huge file into limited 32-bit virtual address space such as in database workloads. Nonlinear mappings are pain to support and it seems there's no legitimate use-cases nowadays since 64-bit systems are widely available. Let's deprecate remap_file_pages() syscall in hope to get rid of code one day. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> --- mm/fremap.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/fremap.c b/mm/fremap.c index 34feba60a17e..af504f443321 100644 --- a/mm/fremap.c +++ b/mm/fremap.c @@ -152,6 +152,9 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, int has_write_lock = 0; vm_flags_t vm_flags = 0; + printk_once(KERN_WARNING "%s (%d) uses depricated " + "remap_file_pages(2) syscall.\n", + current->comm, current->pid); if (prot) return err; /* -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>