| Message ID | 780211.1719318546@warthog.procyon.org.uk (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] netfs: Fix netfs_page_mkwrite() to check folio->mapping is valid | expand |
On Tue, 2024-06-25 at 13:29 +0100, David Howells wrote: > > Fix netfs_page_mkwrite() to check that folio->mapping is valid once > it has > taken the folio lock (as filemap_page_mkwrite() does). Without this, > generic/247 occasionally oopses with something like the following: > > BUG: kernel NULL pointer dereference, address: 0000000000000000 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > > RIP: 0010:trace_event_raw_event_netfs_folio+0x61/0xc0 > ... > Call Trace: > <TASK> > ? __die_body+0x1a/0x60 > ? page_fault_oops+0x6e/0xa0 > ? exc_page_fault+0xc2/0xe0 > ? asm_exc_page_fault+0x22/0x30 > ? trace_event_raw_event_netfs_folio+0x61/0xc0 > trace_netfs_folio+0x39/0x40 > netfs_page_mkwrite+0x14c/0x1d0 > do_page_mkwrite+0x50/0x90 > do_pte_missing+0x184/0x200 > __handle_mm_fault+0x42d/0x500 > handle_mm_fault+0x121/0x1f0 > do_user_addr_fault+0x23e/0x3c0 > exc_page_fault+0xc2/0xe0 > asm_exc_page_fault+0x22/0x30 > > This is due to the invalidate_inode_pages2_range() issued at the end > of the > DIO write interfering with the mmap'd writes. > > Fixes: 102a7e2c598c ("netfs: Allow buffered shared-writeable mmap > through netfs_page_mkwrite()") > Signed-off-by: David Howells <dhowells@redhat.com> > cc: Matthew Wilcox <willy@infradead.org> > cc: Jeff Layton <jlayton@kernel.org> > cc: netfs@lists.linux.dev > cc: v9fs@lists.linux.dev > cc: linux-afs@lists.infradead.org > cc: linux-cifs@vger.kernel.org > cc: linux-mm@kvack.org > cc: linux-fsdevel@vger.kernel.org > --- > Changes > ======= > ver #2) > - Actually unlock the folio rather than returning VM_FAULT_LOCKED > with > VM_FAULT_NOPAGE. > > fs/netfs/buffered_write.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c > index 07bc1fd43530..270f8ebf8328 100644 > --- a/fs/netfs/buffered_write.c > +++ b/fs/netfs/buffered_write.c > @@ -523,6 +523,7 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault > *vmf, struct netfs_group *netfs_gr > struct netfs_group *group; > struct folio *folio = page_folio(vmf->page); > struct file *file = vmf->vma->vm_file; > + struct address_space *mapping = file->f_mapping; > struct inode *inode = file_inode(file); > struct netfs_inode *ictx = netfs_inode(inode); > vm_fault_t ret = VM_FAULT_RETRY; > @@ -534,6 +535,11 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault > *vmf, struct netfs_group *netfs_gr > > if (folio_lock_killable(folio) < 0) > goto out; > + if (folio->mapping != mapping) { > + folio_unlock(folio); > + ret = VM_FAULT_NOPAGE; > + goto out; > + } > > if (folio_wait_writeback_killable(folio)) { > ret = VM_FAULT_LOCKED; > @@ -549,7 +555,7 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault > *vmf, struct netfs_group *netfs_gr > group = netfs_folio_group(folio); > if (group != netfs_group && group != > NETFS_FOLIO_COPY_TO_CACHE) { > folio_unlock(folio); > - err = filemap_fdatawait_range(inode->i_mapping, > + err = filemap_fdatawait_range(mapping, > folio_pos(folio), > folio_pos(folio) + > folio_size(folio)); > switch (err) { > > Reviewed-by: Jeff Layton <jlayton@kernel.org>
On Tue, 25 Jun 2024 13:29:06 +0100, David Howells wrote: > > Fix netfs_page_mkwrite() to check that folio->mapping is valid once it has > taken the folio lock (as filemap_page_mkwrite() does). Without this, > generic/247 occasionally oopses with something like the following: > > BUG: kernel NULL pointer dereference, address: 0000000000000000 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > > [...] Applied to the vfs.fixes branch of the vfs/vfs.git tree. Patches in the vfs.fixes branch should appear in linux-next soon. Please report any outstanding bugs that were missed during review in a new review to the original patch series allowing us to drop it. It's encouraged to provide Acked-bys and Reviewed-bys even though the patch has now been applied. If possible patch trailers will be updated. Note that commit hashes shown below are subject to change due to rebase, trailer updates or similar. If in doubt, please check the listed branch. tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git branch: vfs.fixes [1/1] netfs: Fix netfs_page_mkwrite() to check folio->mapping is valid https://git.kernel.org/vfs/vfs/c/a81c98bfa40c
diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c index 07bc1fd43530..270f8ebf8328 100644 --- a/fs/netfs/buffered_write.c +++ b/fs/netfs/buffered_write.c @@ -523,6 +523,7 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_gr struct netfs_group *group; struct folio *folio = page_folio(vmf->page); struct file *file = vmf->vma->vm_file; + struct address_space *mapping = file->f_mapping; struct inode *inode = file_inode(file); struct netfs_inode *ictx = netfs_inode(inode); vm_fault_t ret = VM_FAULT_RETRY; @@ -534,6 +535,11 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_gr if (folio_lock_killable(folio) < 0) goto out; + if (folio->mapping != mapping) { + folio_unlock(folio); + ret = VM_FAULT_NOPAGE; + goto out; + } if (folio_wait_writeback_killable(folio)) { ret = VM_FAULT_LOCKED; @@ -549,7 +555,7 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_gr group = netfs_folio_group(folio); if (group != netfs_group && group != NETFS_FOLIO_COPY_TO_CACHE) { folio_unlock(folio); - err = filemap_fdatawait_range(inode->i_mapping, + err = filemap_fdatawait_range(mapping, folio_pos(folio), folio_pos(folio) + folio_size(folio)); switch (err) {
Fix netfs_page_mkwrite() to check that folio->mapping is valid once it has taken the folio lock (as filemap_page_mkwrite() does). Without this, generic/247 occasionally oopses with something like the following: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page RIP: 0010:trace_event_raw_event_netfs_folio+0x61/0xc0 ... Call Trace: <TASK> ? __die_body+0x1a/0x60 ? page_fault_oops+0x6e/0xa0 ? exc_page_fault+0xc2/0xe0 ? asm_exc_page_fault+0x22/0x30 ? trace_event_raw_event_netfs_folio+0x61/0xc0 trace_netfs_folio+0x39/0x40 netfs_page_mkwrite+0x14c/0x1d0 do_page_mkwrite+0x50/0x90 do_pte_missing+0x184/0x200 __handle_mm_fault+0x42d/0x500 handle_mm_fault+0x121/0x1f0 do_user_addr_fault+0x23e/0x3c0 exc_page_fault+0xc2/0xe0 asm_exc_page_fault+0x22/0x30 This is due to the invalidate_inode_pages2_range() issued at the end of the DIO write interfering with the mmap'd writes. Fixes: 102a7e2c598c ("netfs: Allow buffered shared-writeable mmap through netfs_page_mkwrite()") Signed-off-by: David Howells <dhowells@redhat.com> cc: Matthew Wilcox <willy@infradead.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: linux-cifs@vger.kernel.org cc: linux-mm@kvack.org cc: linux-fsdevel@vger.kernel.org --- Changes ======= ver #2) - Actually unlock the folio rather than returning VM_FAULT_LOCKED with VM_FAULT_NOPAGE. fs/netfs/buffered_write.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)