Messages in this thread Patch in this message | | | Date | Sun, 8 Jun 2008 21:20:43 +0400 | From | Oleg Nesterov <> | Subject | [PATCH 3/3] do_generic_file_read: s/EINTR/EIO/ if lock_page_killable() fails |
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If lock_page_killable() fails because the task was killed by SIGKILL or any other fatal signal, do_generic_file_read() returns -EIO.
This seems to be OK, because in fact the userspace won't see this error, the task will dequeue SIGKILL and exit.
However, /sbin/init is different, it will dequeue SIGKILL, ignore it, and return to the user-space with the bogus -EIO.
Change the code to return the error code from lock_page_killable(), -EINTR. This doesn't fix the bug, but perhaps makes sense anyway. Imho, with this change the code looks a bit more logical, and the "good" init should handle the spurious EINTR or short read.
Afaics we can also change lock_page_killable() to return -ERESTARTNOINTR, but this can't prevent the short reads.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
--- 26-rc2/mm/filemap.c~3_INIT_READ 2008-05-18 15:44:19.000000000 +0400 +++ 26-rc2/mm/filemap.c 2008-06-08 19:23:51.000000000 +0400 @@ -1000,8 +1000,9 @@ page_ok: page_not_up_to_date: /* Get exclusive access to the page ... */ - if (lock_page_killable(page)) - goto readpage_eio; + error = lock_page_killable(page); + if (unlikely(error)) + goto readpage_error; /* Did it get truncated before we got the lock? */ if (!page->mapping) { @@ -1029,8 +1030,9 @@ readpage: } if (!PageUptodate(page)) { - if (lock_page_killable(page)) - goto readpage_eio; + error = lock_page_killable(page); + if (unlikely(error)) + goto readpage_error; if (!PageUptodate(page)) { if (page->mapping == NULL) { /* @@ -1042,15 +1044,14 @@ readpage: } unlock_page(page); shrink_readahead_size_eio(filp, ra); - goto readpage_eio; + error = -EIO; + goto readpage_error; } unlock_page(page); } goto page_ok; -readpage_eio: - error = -EIO; readpage_error: /* UHHUH! A synchronous read error occurred. Report it */ desc->error = error;
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