On Mon, 2014-12-15 at 14:25 +0000, Luis Henriques wrote: > 3.16.7-ckt3 -stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Steven Capper <steve.capper@xxxxxxxxxx> > > commit ded9477984690d026e46dd75e8157392cea3f13f upstream. > > For LPAE, we have the following means for encoding writable or dirty > ptes: > L_PTE_DIRTY L_PTE_RDONLY > !pte_dirty && !pte_write 0 1 > !pte_dirty && pte_write 0 1 > pte_dirty && !pte_write 1 1 > pte_dirty && pte_write 1 0 > > So we can't distinguish between writeable clean ptes and read only > ptes. This can cause problems with ptes being incorrectly flagged as > read only when they are writeable but not dirty. > > This patch renumbers L_PTE_RDONLY from AP[2] to a software bit #58, > and adds additional logic to set AP[2] whenever the pte is read only > or not dirty. That way we can distinguish between clean writeable ptes > and read only ptes. > > HugeTLB pages will use this new logic automatically. > > We need to add some logic to Transparent HugePages to ensure that they > correctly interpret the revised pgprot permissions (L_PTE_RDONLY has > moved and no longer matches PMD_SECT_AP2). In the process of revising > THP, the names of the PMD software bits have been prefixed with L_ to > make them easier to distinguish from their hardware bit counterparts. > > Signed-off-by: Steve Capper <steve.capper@xxxxxxxxxx> > Reviewed-by: Will Deacon <will.deacon@xxxxxxx> > Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> > Cc: Hou Pengyang <houpengyang@xxxxxxxxxx> > Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx> [...] This one also looks suitable for 3.4 onwards, except that THP was not supported before 3.11. Ben. -- Ben Hutchings The world is coming to an end. Please log off.
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