Looks like its a seam where the drywall comes together and taped. Check closely to make sure. Seen it before. Easy fix if it is. May not have anything to do with your roof.
Should be pretty obvious if its a seam issue. Investigate a little further with a flat tip screwdriver. If you notice tape and drywall screws that's probably the seam where the two pieces meet.
If it is in fact a seam you can redo it. Easy fix if you have finishing drywall skills.
Of course you could always just patch it with some caulk and repaint it. Up to you.
If it's not a seam issue, is there an attic above this room to verify nothing structurally failed?
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