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Message-ID: <1464094742.5939.46.camel@edumazet-glaptop3.roam.corp.google.com> Date: Tue, 24 May 2016 05:59:02 -0700 From: Eric Dumazet <eric.dumazet@...il.com> To: Vladimir Davydov <vdavydov@...tuozzo.com> Cc: Andrew Morton <akpm@...ux-foundation.org>, Alexander Viro <viro@...iv.linux.org.uk>, Johannes Weiner <hannes@...xchg.org>, Michal Hocko <mhocko@...nel.org>, linux-mm@...ck.org, linux-fsdevel@...r.kernel.org, netdev@...r.kernel.org, x86@...nel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH RESEND 7/8] pipe: account to kmemcg On Tue, 2016-05-24 at 11:49 +0300, Vladimir Davydov wrote: > Pipes can consume a significant amount of system memory, hence they > should be accounted to kmemcg. > > This patch marks pipe_inode_info and anonymous pipe buffer page > allocations as __GFP_ACCOUNT so that they would be charged to kmemcg. > Note, since a pipe buffer page can be "stolen" and get reused for other > purposes, including mapping to userspace, we clear PageKmemcg thus > resetting page->_mapcount and uncharge it in anon_pipe_buf_steal, which > is introduced by this patch. > > Signed-off-by: Vladimir Davydov <vdavydov@...tuozzo.com> > Cc: Alexander Viro <viro@...iv.linux.org.uk> > --- > fs/pipe.c | 32 ++++++++++++++++++++++++++------ > 1 file changed, 26 insertions(+), 6 deletions(-) > > diff --git a/fs/pipe.c b/fs/pipe.c > index 0d3f5165cb0b..4b32928f5426 100644 > --- a/fs/pipe.c > +++ b/fs/pipe.c > @@ -21,6 +21,7 @@ > #include <linux/audit.h> > #include <linux/syscalls.h> > #include <linux/fcntl.h> > +#include <linux/memcontrol.h> > > #include <asm/uaccess.h> > #include <asm/ioctls.h> > @@ -137,6 +138,22 @@ static void anon_pipe_buf_release(struct pipe_inode_info *pipe, > put_page(page); > } > > +static int anon_pipe_buf_steal(struct pipe_inode_info *pipe, > + struct pipe_buffer *buf) > +{ > + struct page *page = buf->page; > + > + if (page_count(page) == 1) { This looks racy : some cpu could have temporarily elevated page count. > + if (memcg_kmem_enabled()) { > + memcg_kmem_uncharge(page, 0); > + __ClearPageKmemcg(page); > + } > + __SetPageLocked(page); > + return 0; > + } > + return 1; > +} > +
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