On Sat, 2016-08-27 at 11:31 +0200, Willy Tarreau wrote:
> Greg, Jiri,
>
> I checked Jari's explanation below and found that v3.14.77 and v3.12.62
> are missing the same fix as 3.10. In fact Al's original commit 3d56c25
> ("fix d_walk()/non-delayed __d_free() race") used to mention to check
> this __d_materialise_dentry() function in the Cc: stable line, but this
> got lost during the backports.
>
> Normally all of our 3 kernels need to apply the following patch that
> Ben correctly put in 3.16 and 3.2. I'm fixing the backport in 3.10.103
> right now.
I never did get positive confirmation that this is the right change in
__d_materialise_dentry(). Al, could you please comment?
Ben.
> > Cheers,
> Willy
>
> diff --git a/fs/dcache.c b/fs/dcache.c
> index 2a808fb..2d0b9d2 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -2401,6 +2401,7 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
> > switch_names(dentry, anon);
> > swap(dentry->d_name.hash, anon->d_name.hash);
>
> > + dentry->d_flags |= DCACHE_RCUACCESS;
> > dentry->d_parent = dentry;
> > list_del_init(&dentry->d_child);
> > anon->d_parent = dparent;
>
>
> On Mon, Aug 22, 2016 at 04:56:57PM +0300, Jari Ruusu wrote:
> >
> > This patch for 3.10 branch appears to be missing one important
> >
> > + dentry->d_flags |= DCACHE_RCUACCESS;
> >
> > in fs/dcache.c __d_materialise_dentry() function. When Ben Hutchings
> > backported Al Viro's original fix to stable branches that he maintains,
> > he added that one additional line to both 3.2 and 3.16 branches. Please
> > consider including that additional one line fix for 3.10 stable branch
> > also.
> >
> >
> > Ben Hutchings said this on his 3.2.82-rc1 patch:
> > [bwh: Backported to 3.2:
> > - Adjust context
> > - Also set the flag in __d_materialise_dentry())]
> >
> > http://marc.info/?l=linux-kernel&m=147117565612275&w=2
> >
> >
> > Ben Hutchings said this on his 3.16.37-rc1 patch:
> > [bwh: Backported to 3.16:
> > - Adjust context
> > - Also set the flag in __d_materialise_dentry())]
> >
> > http://marc.info/?l=linux-kernel&m=147117433412006&w=2
> >
> >
> > Also mentioned by Sasha Levin on 3.18 and 4.1 commits:
> > > > Cc: stable@xxxxxxxxxxxxxxx # v3.2+ (and watch out for __d_materialise_dentry())
> >
> > http://marc.info/?l=linux-stable-commits&m=146648034410827&w=2
> > http://marc.info/?l=linux-stable-commits&m=146647471009771&w=2
> >
> > --
> > Jari Ruusu 4096R/8132F189 12D6 4C3A DCDA 0AA4 27BD ACDF F073 3C80 8132 F189
--
Ben Hutchings
[W]e found...that it wasn't as easy to get programs right as we had
thought.
... I realized that a large part of my life from then on was going to
be spent
in finding mistakes in my own programs. - Maurice Wilkes, 1949Attachment:
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