| Message ID | 20160114222544.GB17997@ZenIV.linux.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jan 14, 2016 at 10:25:44PM +0000, Al Viro wrote: > Anyway, mm/shmem.c bit follows. With that + NFS one we ought to be OK > wrt that class of bogosities. I'll write the bits for > Documentation/filesystems/porting (basically, "if you preseed the pagecache > at ->symlink() time, don't put highmem pages there; page_symlink() will > take care of that, provided that inode_nohighmem() is called first") and > push the combined patch to #for-linus. Done and pushed. Please, pull from git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git Shortlog: Al Viro (1): Make sure that highmem pages are not added to symlink page cache Diffstat: Documentation/filesystems/porting | 6 +++++- fs/nfs/dir.c | 5 ++--- mm/shmem.c | 2 +- 3 files changed, 8 insertions(+), 5 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Jan 14, 2016 at 2:25 PM, Al Viro <viro@zeniv.linux.org.uk> wrote: > > For one thing, we'll lose RCU ->get_link() for those. Why couldn't we just do that in the RCU walker? kmap should be fine.. That said, as long as you think it's ok now, I guess I don't care. Having some sanity testing in __add_to_page_cache_locked might be a good safety net. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Jan 14, 2016 at 03:58:22PM -0800, Linus Torvalds wrote: > On Thu, Jan 14, 2016 at 2:25 PM, Al Viro <viro@zeniv.linux.org.uk> wrote: > > > > For one thing, we'll lose RCU ->get_link() for those. > > Why couldn't we just do that in the RCU walker? kmap should be fine.. In map_new_virtual(): __set_current_state(TASK_UNINTERRUPTIBLE); add_wait_queue(pkmap_map_wait, &wait); unlock_kmap(); schedule(); remove_wait_queue(pkmap_map_wait, &wait); lock_kmap(); IOW, not in RCU mode ;-/ > That said, as long as you think it's ok now, I guess I don't care. > Having some sanity testing in __add_to_page_cache_locked might be a > good safety net. That's better as a separate commit, IMO. The thing I'm not sure about is whether we want a BUG() in there - VM_WARN_ON(), perhaps? OTOH, we do have VM_BUG_ON_PAGE() in the same place already... -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/mm/shmem.c b/mm/shmem.c index 5813b7f..642471b 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2469,6 +2469,7 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s inode->i_op = &shmem_short_symlink_operations; inode->i_link = info->symlink; } else { + inode_nohighmem(inode); error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); if (error) { iput(inode); @@ -2476,7 +2477,6 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s } inode->i_mapping->a_ops = &shmem_aops; inode->i_op = &shmem_symlink_inode_operations; - inode_nohighmem(inode); memcpy(page_address(page), symname, len); SetPageUptodate(page); set_page_dirty(page);