[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <20110605134317.GF11521@ZenIV.linux.org.uk>
Date: Sun, 5 Jun 2011 14:43:17 +0100
From: Al Viro <viro@...IV.linux.org.uk>
To: linux-mm@...ck.org
Cc: Mel Gorman <mel@....ul.ie>, linux-kernel@...r.kernel.org
Subject: ENOSPC returned by handle_mm_fault()
When alloc_huge_page() runs afoul of quota, it returns ERR_PTR(-ENOSPC).
Callers do not expect that - hugetlb_cow() returns ENOSPC if it gets that
and so does hugetlb_no_page(). Eventually the thing propagates back to
hugetlb_fault() and is returned by it.
Callers of hugetlb_fault() clearly expect a bitmap of VM_... and
not something from errno.h: one place is
ret = hugetlb_fault(mm, vma, vaddr,
(flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
spin_lock(&mm->page_table_lock);
if (!(ret & VM_FAULT_ERROR))
continue;
and another is handle_mm_fault(), which ends up returning ENOSPC and *its*
callers are definitely not ready to deal with that.
ENOSPC is 28, i.e. VM_FAULT_MAJOR | VM_FAULT_WRITE | VM_FAULT_HWPOISON;
it's also theoretically possible to get ENOMEM if region_chg() ends up
hitting
nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
if (!nrg)
return -ENOMEM;
region_chg() <- vma_needs_reservation() <- alloc_huge_page() and from that
point as with ENOSPC. ENOMEM is 12, i.e. VM_FAULT_MAJOR | VM_FAULT_WRITE...
Am I right assuming that we want VM_FAULT_OOM in both cases?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists