From: Peter Xu <peterx@redhat.com>
To: Yang Shi <shy828301@gmail.com>
Cc: "HORIGUCHI NAOYA(堀口 直也)" <naoya.horiguchi@nec.com>,
"Hugh Dickins" <hughd@google.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
"Matthew Wilcox" <willy@infradead.org>,
"Oscar Salvador" <osalvador@suse.de>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Linux MM" <linux-mm@kvack.org>,
"Linux FS-devel Mailing List" <linux-fsdevel@vger.kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: [v3 PATCH 4/5] mm: shmem: don't truncate page if memory failure happens
Date: Wed, 13 Oct 2021 06:26:55 +0800 [thread overview]
Message-ID: <YWYLr3vOTgLDNiNL@t490s> (raw)
In-Reply-To: <CAHbLzkrJ9YZYUS+T64L9vFzg77qVg2SZ4DBGC013kgGTRvpieA@mail.gmail.com>
On Tue, Oct 12, 2021 at 12:17:33PM -0700, Yang Shi wrote:
> On Mon, Oct 11, 2021 at 6:57 PM Peter Xu <peterx@redhat.com> wrote:
> >
> > On Thu, Sep 30, 2021 at 02:53:10PM -0700, Yang Shi wrote:
> > > diff --git a/mm/shmem.c b/mm/shmem.c
> > > index 88742953532c..75c36b6a405a 100644
> > > --- a/mm/shmem.c
> > > +++ b/mm/shmem.c
> > > @@ -2456,6 +2456,7 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
> > > struct inode *inode = mapping->host;
> > > struct shmem_inode_info *info = SHMEM_I(inode);
> > > pgoff_t index = pos >> PAGE_SHIFT;
> > > + int ret = 0;
> > >
> > > /* i_rwsem is held by caller */
> > > if (unlikely(info->seals & (F_SEAL_GROW |
> > > @@ -2466,7 +2467,17 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
> > > return -EPERM;
> > > }
> > >
> > > - return shmem_getpage(inode, index, pagep, SGP_WRITE);
> > > + ret = shmem_getpage(inode, index, pagep, SGP_WRITE);
> > > +
> > > + if (*pagep) {
> > > + if (PageHWPoison(*pagep)) {
> > > + unlock_page(*pagep);
> > > + put_page(*pagep);
> > > + ret = -EIO;
> > > + }
> > > + }
> > > +
> > > + return ret;
> > > }
> > >
> > > static int
> > > @@ -2555,6 +2566,11 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
> > > unlock_page(page);
> > > }
> > >
> > > + if (page && PageHWPoison(page)) {
> > > + error = -EIO;
> > > + break;
> > > + }
> > > +
> > > /*
> > > * We must evaluate after, since reads (unlike writes)
> > > * are called without i_rwsem protection against truncate
> >
> > [...]
> >
> > > @@ -4193,6 +4216,10 @@ struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
> > > page = ERR_PTR(error);
> > > else
> > > unlock_page(page);
> > > +
> > > + if (PageHWPoison(page))
> > > + page = ERR_PTR(-EIO);
> > > +
> > > return page;
> > > #else
> > > /*
> > > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> > > index 7a9008415534..b688d5327177 100644
> > > --- a/mm/userfaultfd.c
> > > +++ b/mm/userfaultfd.c
> > > @@ -233,6 +233,11 @@ static int mcontinue_atomic_pte(struct mm_struct *dst_mm,
> > > goto out;
> > > }
> > >
> > > + if (PageHWPoison(page)) {
> > > + ret = -EIO;
> > > + goto out_release;
> > > + }
> > > +
> > > ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
> > > page, false, wp_copy);
> > > if (ret)
> > > --
> > > 2.26.2
> > >
> >
> > These are shmem_getpage_gfp() call sites:
> >
> > shmem_getpage[151] return shmem_getpage_gfp(inode, index, pagep, sgp,
> > shmem_fault[2112] err = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, SGP_CACHE,
> > shmem_read_mapping_page_gfp[4188] error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
> >
> > These are further shmem_getpage() call sites:
> >
> > collapse_file[1735] if (shmem_getpage(mapping->host, index, &page,
> > shmem_undo_range[965] shmem_getpage(inode, start - 1, &page, SGP_READ);
> > shmem_undo_range[980] shmem_getpage(inode, end, &page, SGP_READ);
> > shmem_write_begin[2467] return shmem_getpage(inode, index, pagep, SGP_WRITE);
> > shmem_file_read_iter[2544] error = shmem_getpage(inode, index, &page, sgp);
> > shmem_fallocate[2733] error = shmem_getpage(inode, index, &page, SGP_FALLOC);
> > shmem_symlink[3079] error = shmem_getpage(inode, 0, &page, SGP_WRITE);
> > shmem_get_link[3120] error = shmem_getpage(inode, 0, &page, SGP_READ);
> > mcontinue_atomic_pte[235] ret = shmem_getpage(inode, pgoff, &page, SGP_READ);
> >
> > Wondering whether this patch covered all of them.
>
> No, it doesn't need. Not all places care about hwpoison page, for
> example, truncate, hole punch, etc. Only the APIs which return the
> data back to userspace or write back to disk need care about if the
> data is corrupted or not since. This has been elaborated in the cover
> letter.
I see, sorry I missed that. However I still have two entries unsure in above
list that this patch didn't cover (besides fault path, truncate, ...):
collapse_file[1735] if (shmem_getpage(mapping->host, index, &page,
shmem_get_link[3120] error = shmem_getpage(inode, 0, &page, SGP_READ);
IIUC the 1st one is when we want to collapse a file thp, should we stop the
attempt if we see a hwpoison small page?
The 2nd one should be where we had a symlink shmem file and the 1st page which
stores the link got corrupted. Should we fail the get_link() then?
--
Peter Xu
next prev parent reply other threads:[~2021-10-12 22:27 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-30 21:53 [RFC v3 PATCH 0/5] Solve silent data loss caused by poisoned page cache (shmem/tmpfs) Yang Shi
2021-09-30 21:53 ` [v3 PATCH 1/5] mm: hwpoison: remove the unnecessary THP check Yang Shi
2021-10-06 2:35 ` Yang Shi
2021-10-06 4:00 ` Naoya Horiguchi
2021-10-06 17:56 ` Yang Shi
2021-09-30 21:53 ` [v3 PATCH 2/5] mm: filemap: check if THP has hwpoisoned subpage for PMD page fault Yang Shi
2021-10-01 7:23 ` Naoya Horiguchi
2021-10-01 21:07 ` Yang Shi
2021-10-04 14:06 ` Kirill A. Shutemov
2021-10-04 18:17 ` Yang Shi
2021-10-04 19:41 ` Kirill A. Shutemov
2021-10-04 20:13 ` Yang Shi
2021-10-06 19:54 ` Peter Xu
2021-10-06 23:41 ` Yang Shi
2021-10-07 16:14 ` Peter Xu
2021-10-07 18:28 ` Yang Shi
2021-10-08 9:35 ` Kirill A. Shutemov
2021-10-11 22:57 ` Peter Xu
2021-10-06 20:15 ` Peter Xu
2021-10-06 23:57 ` Yang Shi
2021-10-07 16:06 ` Peter Xu
2021-10-07 18:19 ` Yang Shi
2021-10-07 20:27 ` Yang Shi
2021-10-07 21:28 ` Yang Shi
2021-10-12 0:55 ` Peter Xu
2021-10-12 1:44 ` Peter Xu
2021-10-12 18:02 ` Yang Shi
2021-10-12 22:10 ` Peter Xu
2021-10-13 2:48 ` Yang Shi
2021-10-13 3:01 ` Peter Xu
2021-10-13 3:27 ` Yang Shi
2021-10-13 3:41 ` Peter Xu
2021-10-13 21:42 ` Yang Shi
2021-10-13 23:13 ` Peter Xu
2021-10-14 6:54 ` Naoya Horiguchi
2021-10-06 20:18 ` Peter Xu
2021-10-07 2:49 ` Yang Shi
2021-11-01 19:05 ` Naresh Kamboju
2021-11-01 19:26 ` Yang Shi
2021-09-30 21:53 ` [v3 PATCH 3/5] mm: hwpoison: refactor refcount check handling Yang Shi
2021-10-06 22:01 ` Peter Xu
2021-10-07 2:47 ` Yang Shi
2021-10-07 16:18 ` Peter Xu
2021-09-30 21:53 ` [v3 PATCH 4/5] mm: shmem: don't truncate page if memory failure happens Yang Shi
2021-10-01 7:05 ` Naoya Horiguchi
2021-10-01 21:08 ` Yang Shi
2021-10-12 1:57 ` Peter Xu
2021-10-12 19:17 ` Yang Shi
2021-10-12 22:26 ` Peter Xu [this message]
2021-10-13 3:00 ` Yang Shi
2021-10-13 3:06 ` Peter Xu
2021-10-13 3:29 ` Yang Shi
2021-09-30 21:53 ` [v3 PATCH 5/5] mm: hwpoison: handle non-anonymous THP correctly Yang Shi
2021-10-01 7:06 ` Naoya Horiguchi
2021-10-01 21:09 ` Yang Shi
2021-10-13 2:40 ` [RFC v3 PATCH 0/5] Solve silent data loss caused by poisoned page cache (shmem/tmpfs) Peter Xu
2021-10-13 3:09 ` Yang Shi
2021-10-13 3:24 ` Peter Xu
2021-10-14 6:54 ` Naoya Horiguchi
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