[lkml]   [2006]   [Oct]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [patch 2/5] mm: fault vs invalidate/truncate race fix

    On Tue, 10 Oct 2006, Andrew Morton wrote:
    > On Wed, 11 Oct 2006 15:39:22 +1000
    > Nick Piggin <> wrote:
    > > But I see that it does read twice. Do you want that behaviour retained? It
    > > seems like at this level it would be logical to read it once and let lower
    > > layers take care of any retries?
    > argh. Linus has good-sounding reasons for retrying the pagefault-path's
    > read a single time, but I forget what they are. Something to do with
    > networked filesystems? (adds cc)

    Indeed. We _have_ to re-try a failed IO that we didn't start ourselves.

    The original IO could have been started by a person who didn't have
    permissions to actually carry it out successfully, so if you enter with
    the page locked (because somebody else started the IO), and you wait for
    the page and it's not up-to-date afterwards, you absolutely _have_ to try
    the IO, and can only return a real IO error after your _own_ IO has

    There is another issue too: even if the page was marked as having an error
    when we entered (and no longer locked - maybe the IO failed last time
    around), we should _still_ re-try. It might be a temporary error that has
    since gone away, and if we don't re-try, we can end up in the totally
    untenable situation where the kernel makes a soft error into a hard one.

    Neither case simply isn't acceptable. End result: only things like
    read-ahead should actually honor the "page exists but is not up-to-date"
    as a "don't even try".

    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2009-11-18 23:46    [W:0.021 / U:349.800 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site