Hi, I somehow forgot about these patches. The previous version was posted here: http://marc.info/?l=linux-mm&m=142668784122763&w=2. The first attempt was broken but even when fixed it seems like ignoring mapping_gfp_mask in page_cache_read is too fragile because filesystems might use locks in their filemap_fault handlers which could trigger recursion problems as pointed out by Dave http://marc.info/?l=linux-mm&m=142682332032293&w=2. The first patch should be straightforward fix to obey mapping_gfp_mask when allocating for mapping. It can be applied even without the second one. The second patch is an attempt to handle mapping_gfp_mask from the page fault path properly. GFP_IOFS should be safe from he page fault path in general (we would be quite broken otherwise because there are places where GFP_KERNEL is used - e.g. pte allocation). MM will communicate this to the fs layer via struct vm_fault::gfp_mask. If fs needs to change this allocation context in a fs callback it can overwrite this mask. If the code flow gets back to MM we will obey this gfp_mask (e.g. in page_cache_read). This should be more appropriate than following mapping_gfp_mask blindly. See the patch description for more details. I am still not sure this is the right way to go so I am sending this as an RFC so any comments are highly appreciated. Thanks! -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
