| Message ID | 20200916133923.31-1-adrianhuang0701@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2,1/1] dax: Fix stack overflow when mounting fsdax pmem device | expand |
On Wed 16-09-20 21:39:23, Adrian Huang wrote: > From: Adrian Huang <ahuang12@lenovo.com> > > When mounting fsdax pmem device, commit 6180bb446ab6 ("dax: fix > detection of dax support for non-persistent memory block devices") > introduces the stack overflow [1][2]. Here is the call path for > mounting ext4 file system: > ext4_fill_super > bdev_dax_supported > __bdev_dax_supported > dax_supported > generic_fsdax_supported > __generic_fsdax_supported > bdev_dax_supported > > The call path leads to the infinite calling loop, so we cannot > call bdev_dax_supported() in __generic_fsdax_supported(). The sanity > checking of the variable 'dax_dev' is moved prior to the two > bdev_dax_pgoff() checks [3][4]. > > [1] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/thread/BULZHRILK7N2WS2JVISNF2QZNRQK6JU4/ > [2] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/thread/OOZGFY3RNQGTGJJCH52YXCSYIDXMOPXO/ > [3] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/message/SMQW2LY3QHPXOAW76RKNSCGG3QJFO7HT/ > [4] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/message/7E2X6UGX5RQ2ISGYNAF66VLY5BKBFI4M/ > > Fixes: 6180bb446ab6 ("dax: fix detection of dax support for non-persistent memory block devices") > Cc: Coly Li <colyli@suse.de> > Cc: Jan Kara <jack@suse.cz> > Cc: Ira Weiny <ira.weiny@intel.com> > Cc: John Pittman <jpittman@redhat.com> > Cc: Mikulas Patocka <mpatocka@redhat.com> > Cc: Alasdair Kergon <agk@redhat.com> > Cc: Mike Snitzer <snitzer@redhat.com> > Signed-off-by: Adrian Huang <ahuang12@lenovo.com> The patch looks good to me. You can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > v1->v2 > * Remove the checking for the returned value '-EOPNOTSUPP' of > dax_direct_access(). Jan has prepared a patch to address the > issue in dm. > --- > drivers/dax/super.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > index e5767c83ea23..11d0541e6f8f 100644 > --- a/drivers/dax/super.c > +++ b/drivers/dax/super.c > @@ -85,6 +85,12 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev, > return false; > } > > + if (!dax_dev) { > + pr_debug("%s: error: dax unsupported by block device\n", > + bdevname(bdev, buf)); > + return false; > + } > + > err = bdev_dax_pgoff(bdev, start, PAGE_SIZE, &pgoff); > if (err) { > pr_info("%s: error: unaligned partition for dax\n", > @@ -100,12 +106,6 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev, > return false; > } > > - if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) { > - pr_debug("%s: error: dax unsupported by block device\n", > - bdevname(bdev, buf)); > - return false; > - } > - > id = dax_read_lock(); > len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn); > len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn); > -- > 2.17.1 >
On Wed, Sep 16, 2020 at 6:41 AM Adrian Huang <adrianhuang0701@gmail.com> wrote: > > From: Adrian Huang <ahuang12@lenovo.com> > > When mounting fsdax pmem device, commit 6180bb446ab6 ("dax: fix > detection of dax support for non-persistent memory block devices") > introduces the stack overflow [1][2]. Here is the call path for > mounting ext4 file system: > ext4_fill_super > bdev_dax_supported > __bdev_dax_supported > dax_supported > generic_fsdax_supported > __generic_fsdax_supported > bdev_dax_supported > > The call path leads to the infinite calling loop, so we cannot > call bdev_dax_supported() in __generic_fsdax_supported(). The sanity > checking of the variable 'dax_dev' is moved prior to the two > bdev_dax_pgoff() checks [3][4]. Looks good, and passes tests. > [1] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/thread/BULZHRILK7N2WS2JVISNF2QZNRQK6JU4/ > [2] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/thread/OOZGFY3RNQGTGJJCH52YXCSYIDXMOPXO/ > [3] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/message/SMQW2LY3QHPXOAW76RKNSCGG3QJFO7HT/ > [4] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/message/7E2X6UGX5RQ2ISGYNAF66VLY5BKBFI4M/ lists.01.org has already proven to not be reliable for maintaining permanent list archive links. The most reliable way to reference a message is via lore.kernel.org. http://lore.kernel.org/r/$MSG_ID For example your first link is here: http://lore.kernel.org/r/1420999447.1004543.1600055488770.JavaMail.zimbra@redhat.com
diff --git a/drivers/dax/super.c b/drivers/dax/super.c index e5767c83ea23..11d0541e6f8f 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -85,6 +85,12 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev, return false; } + if (!dax_dev) { + pr_debug("%s: error: dax unsupported by block device\n", + bdevname(bdev, buf)); + return false; + } + err = bdev_dax_pgoff(bdev, start, PAGE_SIZE, &pgoff); if (err) { pr_info("%s: error: unaligned partition for dax\n", @@ -100,12 +106,6 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev, return false; } - if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) { - pr_debug("%s: error: dax unsupported by block device\n", - bdevname(bdev, buf)); - return false; - } - id = dax_read_lock(); len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn); len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn);