On Tue, Aug 03, 2021 at 04:06:47PM +0800, Huang, Ying wrote: > As Hugh pointed out, EINVAL isn't an appropriate error code for race > condition. After checking the code, I found that EEXIST is the error > code used for race condition. So I revise the patch as below. If Hugh > doesn't object, can you help to replace the patch with the below one? > > Best Regards, > Huang, Ying > > -----------------------------8<--------------------------------------- > >From e2b281a0b09d34d6463942e214e577ed9357c213 Mon Sep 17 00:00:00 2001 > From: Huang Ying <ying.huang@xxxxxxxxx> > Date: Tue, 3 Aug 2021 10:51:16 +0800 > Subject: [PATCH] shmem_swapin_page(): fix error processing for > get_swap_device() > > Firstly, "-" is missing before the error code. Secondly, EINVAL isn't > the proper error code for the race condition. EEXIST is used in > shmem_swapin_page() for that. So the error code is changed to EEXIST > too. > > Link: https://lkml.kernel.org/r/20210723080000.93953-1-ying.huang@xxxxxxxxx > Fixes: 2efa33fc7f6e ("mm/shmem: fix shmem_swapin() race with swapoff") > Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx> Suggested-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Also, the description is poor. How about: If we hit this rare race, returning EINVAL (or even -EINVAL) would cause the page fault to be handled as a SIGBUS. This is not correct; the page is not missing or unreadable, it has simply changed location. Returning -EEXIST here will cause the lookup to be retried by the caller.
