From: Shaohua Li Date: Fri, 7 Sep 2012 00:17:56 +0000 (+1000) Subject: readahead: fault retry breaks mmap file read random detection X-Git-Tag: next-20120907~1^2~204 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e35b7fb897818210424843dbf82741bf23d4bc43;p=karo-tx-linux.git readahead: fault retry breaks mmap file read random detection .fault now can retry. The retry can break state machine of .fault. In filemap_fault, if page is miss, ra->mmap_miss is increased. In the second try, since the page is in page cache now, ra->mmap_miss is decreased. And these are done in one fault, so we can't detect random mmap file access. Add a new flag to indicate .fault is tried once. In the second try, skip ra->mmap_miss decreasing. The filemap_fault state machine is ok with it. I only tested x86, didn't test other archs, but looks the change for other archs is obvious, but who knows :) Signed-off-by: Shaohua Li Cc: Rik van Riel Cc: Wu Fengguang Signed-off-by: Andrew Morton --- diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index c3bd83450227..5dbf13f954f6 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -336,6 +336,7 @@ retry: /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk * of starvation. */ flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; goto retry; } } diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c index b92e60958617..b2f2d2d66849 100644 --- a/arch/avr32/mm/fault.c +++ b/arch/avr32/mm/fault.c @@ -152,6 +152,7 @@ good_area: tsk->min_flt++; if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* * No need to up_read(&mm->mmap_sem) as we would have diff --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c index 45fd542cf173..73312ab6c696 100644 --- a/arch/cris/mm/fault.c +++ b/arch/cris/mm/fault.c @@ -186,6 +186,7 @@ retry: tsk->min_flt++; if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* * No need to up_read(&mm->mmap_sem) as we would diff --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c index 06695cc4fe58..513b74cb397e 100644 --- a/arch/hexagon/mm/vm_fault.c +++ b/arch/hexagon/mm/vm_fault.c @@ -113,6 +113,7 @@ good_area: current->min_flt++; if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; goto retry; } } diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c index 8443daf4f515..6cf0341f978e 100644 --- a/arch/ia64/mm/fault.c +++ b/arch/ia64/mm/fault.c @@ -184,6 +184,7 @@ retry: current->min_flt++; if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* No need to up_read(&mm->mmap_sem) as we would * have already released it in __lock_page_or_retry diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c index aeebbb7b30f0..a563727806bf 100644 --- a/arch/m68k/mm/fault.c +++ b/arch/m68k/mm/fault.c @@ -170,6 +170,7 @@ good_area: /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk * of starvation. */ flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* * No need to up_read(&mm->mmap_sem) as we would diff --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c index eb365d6795fa..714b35a9c4f7 100644 --- a/arch/microblaze/mm/fault.c +++ b/arch/microblaze/mm/fault.c @@ -233,6 +233,7 @@ good_area: current->min_flt++; if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* * No need to up_read(&mm->mmap_sem) as we would diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c index c14f6dfed995..9f513486af10 100644 --- a/arch/mips/mm/fault.c +++ b/arch/mips/mm/fault.c @@ -171,6 +171,7 @@ good_area: } if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* * No need to up_read(&mm->mmap_sem) as we would diff --git a/arch/openrisc/mm/fault.c b/arch/openrisc/mm/fault.c index 40f850e9766c..e2bfafce66c5 100644 --- a/arch/openrisc/mm/fault.c +++ b/arch/openrisc/mm/fault.c @@ -183,6 +183,7 @@ good_area: tsk->min_flt++; if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* No need to up_read(&mm->mmap_sem) as we would * have already released it in __lock_page_or_retry diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 995f924e007f..183c787e862d 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -451,6 +451,7 @@ good_area: /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk * of starvation. */ flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; goto retry; } } diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index ac9122ca1152..04ad4001a289 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -367,6 +367,7 @@ retry: /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk * of starvation. */ flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; down_read(&mm->mmap_sem); goto retry; } diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c index 3bdc1ad9a341..cbbdcad8fcb3 100644 --- a/arch/sh/mm/fault.c +++ b/arch/sh/mm/fault.c @@ -504,6 +504,7 @@ good_area: } if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* * No need to up_read(&mm->mmap_sem) as we would diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c index 77ac917be152..e98bfda205a2 100644 --- a/arch/sparc/mm/fault_32.c +++ b/arch/sparc/mm/fault_32.c @@ -265,6 +265,7 @@ good_area: } if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* No need to up_read(&mm->mmap_sem) as we would * have already released it in __lock_page_or_retry diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c index 1fe0429b6314..413d29263304 100644 --- a/arch/sparc/mm/fault_64.c +++ b/arch/sparc/mm/fault_64.c @@ -452,6 +452,7 @@ good_area: } if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* No need to up_read(&mm->mmap_sem) as we would * have already released it in __lock_page_or_retry diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c index 84ce7abbf5af..fe811fa5f1b9 100644 --- a/arch/tile/mm/fault.c +++ b/arch/tile/mm/fault.c @@ -454,6 +454,7 @@ good_area: tsk->min_flt++; if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* * No need to up_read(&mm->mmap_sem) as we would diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c index 0353b98ae35a..0f00e9c82080 100644 --- a/arch/um/kernel/trap.c +++ b/arch/um/kernel/trap.c @@ -89,6 +89,7 @@ good_area: current->min_flt++; if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; goto retry; } diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 7dde46d68a25..d57ca71e1245 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1202,6 +1202,7 @@ good_area: /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk * of starvation. */ flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; goto retry; } } diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c index 5a74c53bc69c..2c2f710ed1dc 100644 --- a/arch/xtensa/mm/fault.c +++ b/arch/xtensa/mm/fault.c @@ -126,6 +126,7 @@ good_area: current->min_flt++; if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* No need to up_read(&mm->mmap_sem) as we would * have already released it in __lock_page_or_retry diff --git a/include/linux/mm.h b/include/linux/mm.h index 311be906b57d..c861ef121b74 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -157,6 +157,7 @@ extern pgprot_t protection_map[16]; #define FAULT_FLAG_ALLOW_RETRY 0x08 /* Retry fault if blocking */ #define FAULT_FLAG_RETRY_NOWAIT 0x10 /* Don't drop mmap_sem and wait when retrying */ #define FAULT_FLAG_KILLABLE 0x20 /* The fault task is in SIGKILL killable region */ +#define FAULT_FLAG_TRIED 0x40 /* second try */ /* * This interface is used by x86 PAT code to identify a pfn mapping that is diff --git a/mm/filemap.c b/mm/filemap.c index 384344575c37..94a50bfa2f99 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1607,13 +1607,13 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) * Do we have something in the page cache already? */ page = find_get_page(mapping, offset); - if (likely(page)) { + if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) { /* * We found the page, so try async readahead before * waiting for the lock. */ do_async_mmap_readahead(vma, ra, file, page, offset); - } else { + } else if (!page) { /* No page in the page cache at all */ do_sync_mmap_readahead(vma, ra, file, offset); count_vm_event(PGMAJFAULT);